95 Jimmy 4.3 Vortec starting problems - weird

This problem has been coming and going. Sometimes it will fire right up & runs fine. Other times you have to crank it ahile and it will fire up slowly, then runs fine. Last night wouldn't fire a lick. Put a charger on the battery (ran it down), tried again today - nothing. This I have do so far: New fuel pump/filter/lines/ ,new wires, new plugs, replaced the EGR Checked all connections (vacuum/electrical). I sprayed a llittle starting fluid in, it fired and ran fine. Engine has less than 70K miles on it (original lost a oil line and *BAM* 3 thrown rods....). I'm stumped. Any suggestions?
TY in advance...
Jon

Pull your upper plenum and check for washing... Run a can of seafoam through the system.

Thanks for the info! There isn't anything "tricky" about removing the plenum is there? I haven't done that before. On the original engine that blew up, I saw the inside of the plenum and it was washed due to the injector spider assy. leaking, so I know what that looks like....

you could also have a concern with the fuel pump relay intermittently not working . thy turning the key on first and listen for the pump to run before cranking . it sould run for 3 seconds then stop if comnputer does not see a crank signal. if no pump running and long crank time then starts the pump may be coming on after the oil pressure uint see pressure which will connect the fuel pump circuit on most cars and truck gm makes . this may explain the long crank time. how ever i do not have my schematic in front of me to be sure on your truck. check your fuel pump wiring schematic to be sure. i beleive once the computer sees pressure from the oil sender it turns off the relay.

Getting the plenum off isn't hard, just tedious with all the other stuff you have to unbolt first. I had a similar hard-starting problem on my '96 and it ended up being the fuel pressure regulator which is right in there on the back side of the injector assembly. Measure your fuel pressure...if it's below 57psi, change the regulator. Hope this helps!

Thanks for all the info guys! I don't think it is the fuel pump or the relay because it will run once it fires up...I'll double check all of that though. I'll take the plenum off and give it a good eyeballing. I was wondering about the regulator... It kind of acts like it isn't getting enough pressure to send gas thru the injectors..? One thing that has me baffled is if the regulator was bad, once it fires would this some how overcome that problem and send gas to the injectors? I sure miss the old days of a carburator... a lot easier to figure out.

Thanks again guys!
Jon

I'm getting a regulator & a 10mm deep socket (I have ever one but the friggin 10mm) tonight and tearing into this tomorrow. This place rocks! I just hope THAT IS the problem, but from all the links posted by Blazee it sure sounds like it. I will post results and findings.

Thanks again!
Jon

OK, I changed the regulator AND found a bad vacuum line going to the intake manifold. Inside the plenum didn't look like it was washed out anywhere. BTW, THANKS for the thread on replaciing the regulator!!! That made this job a helluva lot easier! :) I also replaced the PCV valve, just for good measure. I fired it up & it fired! I drove it tonight and fired it up 3 or 4 times w/o any real problems, then the last time I tried it, it was acting wierd again. Crank about 4-5 times, turn the key off, and crank again - this time it fired up & I made it home. During the drive, it acted a lil hesitant at times, but idled fine. Does this sound like some sort of sensor? Here is what I have replced:

Fuel pump
Lines to fuel pump
Sensing unit (pump assy)
fuel filter
regulator
EGR valve
cap/rotor/wires
plugs (all but #3 - I;m working on it!) and all but 1 looked pretty good & it was only a lil fouled

I'm stumped. Any ideas? Do any of you guys know how to test the sensors?


Lost in ohio... :(

Tnx!
Jon

I can point you in the right direction for the #3 plug. You'll find several ways in other posts. My preference is to move the intermediate steering shaft aside.
Briefy as follows-
wheels straight, steering lock off. Unsnap the black plastic cover where the shaft connects to the steering box, remove the bolt (11mm), telescope the steering shaft in and angle it out of the way.

Other ways I've read include 1- accessing through the fender wheel with proper combination of wrenches, 2-or using a suitably angled box wrench directly on the plug base to loosen, then use your fingers.

I am curious to see what you find with the starting issues as my 95 is developing starting issues now. I haven't gone through all the commons items yet.

remember in my earlier post about the fuel pump relaymay be intermittently not working which would cause long crank time till the oil sender see's pressure it turns on the fuel pump power circuit. locate fuel pump relay and have test light or multimeter reading wnd when con ern happens to test if relay is sending power to and if not don't forget to check the primary side of relay to make sure it is getting signal to turn on relay. remember to use wiring schematic to chack the correct circuits. please post results, john

excuse above post for not useing spell check

OK here is where I'm at. I took my truck to a big garage (city) and had a friend hook up a bazillion dollar scanner to the computer. NO codes, none whatsoever. I'm still having to spray starting fluid in to get it running. IAlthough the battery seems OK, I'm replacing it.I am (almost) completely convinced that this is the problem. I just can't find anything wrong or anything bad. If this fixes it, I am gonna have this stored in memory FOREVER. I talked to probably 10 mechanics who grilled me over this, and they are buffaloed too. Only thing left is the friggin battery.Every question they asked was answered with a "I did that". It runs fine once started...so it HAS to be the battery, right? I'll post tomorrow once I have that done.

I just want to thank EVERYONE on this board who have helped me on this problem. I'm a LOT more familiar (although I don't know if thats good :) ) with this 4.3 Vortec now. I'm gaining some confidence.

God, PLEASE let it be the battery...otherwise I'm completely lost.

Thanks guys....
Jon

OK here is where I'm at. I took my truck to a big garage (city) and had a friend hook up a bazillion dollar scanner to the computer. NO codes, none whatsoever. I'm still having to spray starting fluid in to get it running. IAlthough the battery seems OK, I'm replacing it.I am (almost) completely convinced that this is the problem. I just can't find anything wrong or anything bad. If this fixes it, I am gonna have this stored in memory FOREVER. I talked to probably 10 mechanics who grilled me over this, and they are buffaloed too. Only thing left is the friggin battery.Every question they asked was answered with a "I did that". It runs fine once started...so it HAS to be the battery, right? I'll post tomorrow once I have that done.

I just want to thank EVERYONE on this board who have helped me on this problem. I'm a LOT more familiar (although I don't know if thats good :) ) with this 4.3 Vortec now. I'm gaining some confidence.

God, PLEASE let it be the battery...otherwise I'm completely lost.

Thanks guys....
Jon
Your problems are consistant with a low fuel pressure condition. You need a minimum of 60 psi for trouble free operation. 54 - 60 PSI will normally cause hard starting. Below 54 will usually only start with staring fluid. Below 43 PSI and the engine will not run at all.

Low fuel pressure at startup can be caused by several things. A weak battery, a weak fuel pump, clogged fuel filter, leaking nut kit, and/or leaking regulator.

If you didn't see any signs of leaking when you had the plenum off, then you can probably eliminate the regulator and nut kit.

This leaves the battery, fuel pump, and/or fuel filter. Just because the fuel pump and filter are relatively new doesn't mean that they should be over looked. A fuel pressure test with the key on and engine off should help trace which is the problem.

Here's another thread where the problem ended up being the battery, There's also a short explaination as to why it causes a hard start:
http://www.automotiveforums.com/vbulletin/showthread.php?t=568768

Well, the new battery didn't fix it. I am borrowing a fuel pressure test guage today and am gonna check the pressure. I hope it isn't the new OEM pump in the tank....I also ran some Seafoam thru the gas just for the heck of it. I'll post the results of the pressure test. I HAVE to be getting close....

Thanks again! :)
Jon

I went to my buddies house today and stuck a fuel pressure guage on it - now here is a potential problem - we dropped tha damn thing several times & broke the plxiglass front to the meter (kept falling off the inside of the hood), so not sure this thing is still accurate. I turned the key on & it jumped to 60 PSI right away, then dropped to about 20 PSI. We tried this several times, and basically the same thing. I can start it only after letting the pump cycle then shut off. After that, maybe a lil slow, it fires and runs fine. I plan on getting a fuel pressure gusage of my own & re-checking. My question is, if the pressure really dropped to 20 PSI, would it even run at all? I'm starting to think nut kit. When I had the intake manifold off, I didn't see any real signs of washing, except that area was a little cleaner than the rest of the manifold. This engine has less than 50K miles on it, so maybe this untrained eye wouldn't catch it? On a scale of 1-10 on the amount of carbon & varnish on the manifold, I would say this area was about 1 cleaner than the rest of the manifold. Nothing like the last engine where the drivers side was shiny clean & the passenger side was about a 7. I'm pretty confident with taking the intake off now. Should I try the nut kit? Would there be any other indications this was leaking?

Whew...

Thanks again!
Jon

Before you do the nut kit, take off the upper plenum, or upper intake. The pressure is too low for it to start, 20psi is too low. Like blaze mentioned, there could be several reasons why your getting the low drop in pressure. Going back to the upper intake, take it off and take a look whats going on under there. Get a helper and with the upper plenum off, get them to turn the key to the "on" position ONLY, don't start it, just to the on position. As the key is turned, watch for leaks, if the nut kit/lines are leaking, you will see it. Either way if you see washing, you know you have an injector system problem.

If the gauge is still functional, then the initial 60 psi reading means a good fuel pump. A subsequent loss in pressure could mean a leak in the system somewhere, an incorrectly installed or bad regulator, or nut kit (BTW, what exactly IS a nut kit?). First, try the gauge on another truck to see if it's good. If so, then I'd suggest rechecking your install...something may have come loose or an o-ring isn't quite seated or cracked. We'll get to the bottom of this, or the bottom or your wallet!

As others have stated the pressure is too low. The high initial pressure that drops drastically would indicate a leak in the system. Most likely causes would be a leaking injector, regulator, nut kit, and/or pulsator. Personally, I would now check the pressure at the filter itself, this will let you know where the problem is. If the pressure still drops, then you know the problem is the tank, which would probably be the pulsator. In the pressure doesn't drop, then the problem is most likely in the plenum.

OK, I might just have to do the remove the plenum thing. Evere since I deliberatly turn the ignition on & allow the pump to run for the initial pressure build up, I am getting it started every time. If I get in & turn the igintion on w/o allowing the pump to build initial pressure, it won't fire. I'm suspecting a small leak somewhere. It still runs fine if I just slow down the starting process a little bit.

I learned here that the nut kit is the set of lines that connect the fuel lines to the injector assy. It is under the intake plenum. They are 2 white hard (plastic?) lines. I saw one on ebay for about $90. I guess the best way to test them would be to remove the intake and do as described above by blazes9395. At least at this point, I'm not afraid of driving it! :)

Hey guys. My wife's 1993 Jimmy is having similar issues.

It developed over the course of a month or so from easy to start to hard to start. Now in order to get it to start you have to try for a couple minutes or hook it up to an external secondary car battery through jumper cables to get it to start.

I've replaced the plugs, checked the wires, changed the distributer cap, changed the fuel filter, and checked all the fluids before I really started getting concerned.

I bought a fuel pressure guage and hooked it up to the schrader valve. The pump hits 60ish and then - SOMETIMES drops off to below 50 and sometimes holds at 55. When the car is running it runs fine.

I've had the alternator, batter, and starter all checked out at autozone - they are all good. I would think this was a weak battery because of the fact that whenever I hook up a set of cables it will start in the first or second time. However - yesterday I swapped a 900 cranking amp battery from my Grand Prix into her Jimmy and put her 700 cranking amp battery in my Grand prix. The same problem stayed with the Jimmy even with the switched batteries. Now here's the odd part. Connect them via jumper cables and whalla ! instant start. The voltage doesn't change on the jimmy's guage when I connect the two? It just doesn't make sense.

After reading this thread it looks like it could be several things. The problem is that it seems very intermittent. The fuel pressure drops sometimes, doens't drop other times. The one key thing is that once it starts one time....It will start easily until it gets cold again - which makes me think it must be some sort of relay somewhere?????

I read in teh chilton's manual that the fuel pump relay may need to be changed. But I don't know where that is???? It says in the convieniece center in the middle of the dash but I see no such thing??? Any ideas? Things next to try - I don't know what much else to do here????

If I remember correctly, the relay is inside the glovebox, behind a panel. When I get a chance, I'll get the manual out and verify that for you. How do the connections look to the battery and have you checked and cleaned the ground connection? I had a bad ground to the frame or chassis once that was a PITA.

Jon

If I remember correctly, the relay is inside the glovebox, behind a panel. When I get a chance, I'll get the manual out and verify that for you. How do the connections look to the battery and have you checked and cleaned the ground connection? I had a bad ground to the frame or chassis once that was a PITA.

Jon

we couldn't find that fuel pump relay behind this panel, and I don't see a convieiniece center anywhere like the chiltons says????

Any ideas where this fuel pump relay resides?

I just looked at my 95 and the relay is located in the panel in the glove box behine a panel marked "relay access" - the panel is on the drivers side of the box. There are 2 located there, small black relays. I did a google search on this and I saw several places that say the same thing. I replaced mine a few years ago when I had pump problems. Hope that helps.

Oh yea, BTW the owners manual and my Hynes book don't list this. Why? I don't know what the big secret is.... :(

My wife and I took apart the whole dash this morning only to find out they are in the engine compartment on the driver side front firewall. I even went to a dealership to ask where they were. Supposedly on the one we have it is on the drivers side wheel well according to the dealer - wasn't there.

According to our chiltons it was in the convienience center - wasn't there.

Sorta odd??? I bought a new one from autozone --will try this solution tonight.

That IS weird. Is your Jimmy a 4X4? Maybe they did things differently?

it is a jimmy 4x4....

I still can't figure out the problem. Replaced teh Fuel pump relay - no change. It's getting worse I can't start it at all now practically.

I took of the intake air/fuel cylinder thing - and peeked inside. It did NOT smell gassy. I attempted to start the car as well as just turn the key to where the fuel pump went active, I could neither hear nor smell gas leaking. So I don't really think this is a fuel regulator or intake "area" problem.

Fuel pump the next bet?

I think the next possiblility would be the...get this it's so obvious...the Fuel Injector Cold Start Valve. Had to look it up and don't ask me where it is. Either it is stuck or a bad circuit. Needing a jump from a healthy battery might indicate an electrical issue or just that it needs the extra juice to get it to move.

Jdm-
OH MAN...you mean there is YET another part to this engine I haven't heard about!? :( I haven't seen anything about a cold start valve on a '95 Jimmy....PLEASE tell me this isn't something I should replace! My book dosn't reference one ( a Haynes book)

Hey Megs, have you tried to get it to fire with a shot of starting fluid in the intake? When mine was practically DOA, that was the only way I could get it to fire. Give it a shot & let us know if it does fire & will run OK if it does... I'm feeling ur pain, BELIEVE me, I've been battling mine for over 6 weeks now - BUT It will start, stop, and all the lights work NOW! :) :) :)

This is getting confusing dealing with two different truck setups *sigh*. The '93 using a TBI injection system and the '95 using a CMFI system...you cannot compare the two beyond their basic operation, but they both do utilize some of the same sensors and valves. I will retract the coment about the cold start valve...I was premature in saying there definitely was one on these trucks unless someone else can back me, but I cannot find one on any version of injection system for the Jimmy.

That being said, if the '95 starting issue is resolved then this thread should be closed. If not, then it seems the only things left to check are the injectors, the poppet valves, the spider unit itself, and the fuel pulsator. Something in the system isn't keeping the fuel lines pressurized.

For the '93, I would look at the injectors, regulator, . If you're cranking and you're not smelling ANY gas from the TBI throat, there ain't no gas goin' in...simple as that. A fuel pressure check would help to diagnose which end to look at.

I can see why this is confusing...mine is a 4.3 CMFI Vortec. Took me awhile to finally get it right.

The 93 is also CMFI injected. 4.3 Vortec - Vin W.

The 93 is also CMFI injected. 4.3 Vortec - Vin W.

Actually it's CPI (Central port injectected) wheras 96+ is CSFI/CMFI (Central sequential fuel injection, or Cental Multiport Fuel Injection if the upgrade has been don)

Ok. Now I'm really confused. I thought mine was CMFI (1995). I have a central "control" in the intake with a spyder assy. attached to that. I replaced the regulator on the back of the "central" part per info. in the FAQ's. Please tell me exactly what I have! I don't wanna look too stupid.... ;)

Thanks!
Jon

Ok. Now I'm really confused. I thought mine was CMFI (1995). I have a central "control" in the intake with a spyder assy. attached to that. I replaced the regulator on the back of the "central" part per info. in the FAQ's. Please tell me exactly what I have! I don't wanna look too stupid.... ;)

Thanks!
Jon

Yours is CPI (Central port injection). It uses a central spider assembly that batch fires (fires all injectors at once)

96+ CSFI/CMFI is similar in concept but each injector fires individualy based on rotor position (165432)

according to the chilton I do have a 93 CMFI - we just verified tonight, and according to the chilton there is no CPI??????

anyway

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I took off the upper manifold, there is fuel sitting in the bottom of the fuel pump regulator side. This could be a problem. I'm not sure what this means...

Here are a few pics. Does anyone have any thoughts?

http://www.geocities.com/jvonengeln/gmc.jpg

http://www.geocities.com/jvonengeln/GMC2.jpg

http://www.geocities.com/jvonengeln/GMC3.jpg



also there is a thread dedicated to my problem, but no one has responded!?!?!?!?!?

http://www.automotiveforums.com/vbulletin/showthread.php?t=575706&page=3

in a previous post on 96-up 4.3L with W code, gm uses 1 term, CSFI. if the customer complains during warrenty about rough idle/hard starting, there is a clean and inspect procedure.
if customer still complaines under warranty, there is a list of conversion parts that will re-fit it to CMFI. as old master and blazee have explained, the conversion does 1 main thing usefull, it eliminates the popet injectors with more reliable and less high maintenance injectors and a new MFI module. i have been trying to see it this bulletin turned into a factory upgrade and what year it started, but i have had no luck so far. i do know that my 2001 still has CSFI, and i plan to do the mod as soon as the outside temp. here in south florida drops, as i have no carport or garage, and i ain't paying 4 hours shop rate to put in 275USD worth of parts. the bulletin is fairly well illistrated and all the needed gm p/n's are there. the only part of the cleaning i cant do is the nitrogen bottle blow down, but if i do the mod, thats not needed. so, if you are medium mechanically inclined and want to eliminate the future hassle of popet injectors misfiring and needing extra maint., i checked gmpartsdirect, and the parts including oring sealer, cleaner and the spider assembly and mod are $275+-USD and shipping. my $o.o2, its worth it to get that off my mind for the next 50,000 mi's.:2cents::2cents::icon16::icon16:

[quote=Megs1082]according to the chilton I do have a 93 CMFI - we just verified tonight, and according to the chilton there is no CPI??????

anyway

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look at the how-to that's posted...

Your pics don't work

Another reason I don't like chilton manuals...

CPI=Central Port Injection...92-95 4.3 motors

CSFI=Central Sequential Fuel Injection 96-2000

CMFI=Central Multiport Fuel Injection-2000-2004 Standard, 96-1999 if you had injection problems (clogged, stuck open) and had the system upgraded. This was actually a recall issue for california I believe.


This is a CPI motor and CPI unit.. See thread here for more pictures...http://www.automotiveforums.com/vbulletin/showthread.php?t=503238&highlight=regulator

http://www.pghconsulting.net/teal/cpi/cpi3.jpg

CSFI

http://static.zoovy.com/img/tunertoys/-/C/cicsfi_96_02_480.jpg

CMFI

http://lindertech.com/images/csfi_minis.jpg

(Note, the CMFI above is the 8 cylinder version, no diff in the 6 really except less 2 nozzles) CMFI will work in CSFI motors w/ the conversion kit

OK, according to what I'm hearing and seeing, I have a CPI engine. THANK YOU guys for clearing that up for me! :) I used that info from the FAQ section to replace my regulator.

This place rocks.... :)

yes from your pix this is a CPI unit. if it was starting with a jump but not on its own with a new battery there is a possibility you are drawing to much current and the voltage is dropping down to around 10 to 9 volts during cranking and the computer will not function when voltage drops this low there for no fuel injection however you may still get spark because it starts with the ignition module then switches to bypass for computed timing once the truck starts. check with a vat-40 tester if possible or two meters to check amp draw and how low voltage goes when cranking and if it is dropping to the voltages above ( around 9 to 10 volts0 then your starter is drawing to much current . a normal starter should draw between 125 and 175 amps. if more and volts dropping then this would explain why is starts with a jump as it is getting the additional ampsand voltage from your wifes truck.at this point replace the starter. if this checks ok then the test for the cpi is as follows . check fuel pressure if between 55 to 60 psi with key on engine off this is normal then you will need to do a fuel volume test . most quality gauges have this. there will be a small dia. hose with a valve coming off the gauge. get a 1 QT motor oil bottle with the see through edge and place hose in bottle and disconnect primary connector at ignition coil and have someone crank engine. with a watch time the fuel going into the bottle for 30 seconds . in 30 sec's normal volume should always be 1 pint or 1/2 a qt. if this is what you have replace your CPI . if you have the pressure but insufficent volume then your regulator is working and you will need to replace your fuel filter and if that does not work your fuel pump is done. thanks for listening, john harrier 20 year master machanic in michigan.

Well, if you read at the beggining of the thread, he states it fires fine when he sprays starter fluid or gas down the throttlebody, he has a new pump, etc etc. Basically he has lost pressure somewhere. Either in the nut kit or regulator, the issue is not a voltage one, the issue is not getting fuel. The only thing at this point that could combine the two is if the CPI is completely shot or the connector is bad.

What would be the benefit of converting to a CMFI type system as opposed to the CPI? I know one thing, the spyder assy. on the CPI units look a lot less durable than the CMFI judging from the photos. Can this be done? The $350 or so for that cheap looking spyder for the CPI is mighty pricey...

Just curious.

Thanks! :)
Jon

they're both durable...


To upgrade to the CMFI you would need to swap out the following with 96+

Heads
Lower intake
Upper intake
Throttle body
EGR system
Engine Harness
ECM
Various sensors

A few other things

Well, that settles that. I'm sticking with what I have.

Thanks for the info!
Jon :)

as far as durability goes a CPI has only one injector and a cmpi has 6 micro injectors. either way if the cpi injector goes bad or just one of the micro injectors goes bad you still have to change the CPi or CMPI as the micro injectors and not replacable sperately. once you solve your concern you will be happy with your CPI again.

The nice thing about using the newer style MPFI kit on the 96+ though is that you can replace individual injectors.

So what I "think" I'm hearing, the CPI has one injector, and the spider assy. is delivering the fuel to the cylinders...all at once? Is that right? I replaced the regulator on the injector...now I'm all confused... :( Damn, I miss the old style engines....

So what I "think" I'm hearing, the CPI has one injector, and the spider assy. is delivering the fuel to the cylinders...all at once? Is that right? I replaced the regulator on the injector...now I'm all confused... :( Damn, I miss the old style engines....

Correct,the CPI (92-95) Is a batch fired system...

yes from your pix this is a CPI unit. if it was starting with a jump but not on its own with a new battery there is a possibility you are drawing to much current and the voltage is dropping down to around 10 to 9 volts during cranking and the computer will not function when voltage drops this low there for no fuel injection however you may still get spark because it starts with the ignition module then switches to bypass for computed timing once the truck starts. check with a vat-40 tester if possible or two meters to check amp draw and how low voltage goes when cranking and if it is dropping to the voltages above ( around 9 to 10 volts0 then your starter is drawing to much current . a normal starter should draw between 125 and 175 amps. if more and volts dropping then this would explain why is starts with a jump as it is getting the additional ampsand voltage from your wifes truck.at this point replace the starter. if this checks ok then the test for the cpi is as follows . check fuel pressure if between 55 to 60 psi with key on engine off this is normal then you will need to do a fuel volume test . most quality gauges have this. there will be a small dia. hose with a valve coming off the gauge. get a 1 QT motor oil bottle with the see through edge and place hose in bottle and disconnect primary connector at ignition coil and have someone crank engine. with a watch time the fuel going into the bottle for 30 seconds . in 30 sec's normal volume should always be 1 pint or 1/2 a qt. if this is what you have replace your CPI . if you have the pressure but insufficent volume then your regulator is working and you will need to replace your fuel filter and if that does not work your fuel pump is done. thanks for listening, john harrier 20 year master machanic in michigan.


Guys,

My problem on the 1993 Jimmy isn't fixed. I replaced the regulator and it still won't start. I tried a couple more things I need to report on.

Batkoach- I appreciate your advice so far - read what I've tested here and see if you can offer any further direction.

I took a voltmeter and checked the voltage at the battery when the car is trying to start. It never drops below 11 volts and the battery sits normally at 12.4ish. The reason I checked this is that one guy said when the starters begin wearing out they suck up a lot more amperage - if they suck up too much amperage they will drop the voltage on the battery. If the battery voltage drops to less than 9 or 10 volts sometimes the computer won't function right and so it won't start because the computer is not acting correctly - This would explain why the car runs good when it actually is running because the battery is at 14.4 volts and so supplying enough juice to let the computer run perfectly. ALAS, this is not my problem nor a fix because my voltage never drops below 11 volts.

I checked a couple other things. Someone suggest a fuel pump volume test. They said the fuel pump here should put out about 1 quart of gas in 30 seconds. I'm not sure how scientific my test of this was because I'm not sure that the schrader valve/pressure fuel gauge release button allows full flow, but I tried this and let the car try to start with the fuel pressure gauge attached to the schrader valve and the bypass hose hooked up. I only gathered 10 ounces in 30 seconds. LIke I said, I'm not sure this is accurate because I don't know if the bleed valve on the fuel pressure gauge is of a diameter to let full flow out, BUT that 10 ounces is low compared to the 32 ounces it should have????.

3rd test -- Someone else said that I should find a point along the fuel lines with rubber hose. Turn the key to the ignition point (1 click shy of starting to where the pressure builds, and then turn off the key. Then pinch the hose and have another person check the fuel pressure at the shcrader valve. If the pressure remains the same at the valve you aren't leaking on the engine/injector side, and if it drops you are. Likewise, after a couple minutes, when you release the pinch, if the fuel pressure at the guage drops really low it means the pump isn't holding pressure in the tank. This is what happened. I pinched the line when the pressure guage read 57. I held for two minutes. The line pressure dropped to about 56.5. I released the pinch after about 2 minutes and the pressure dropped to 30ish PSI. That seems to point to a bad/dying fuel pump???

Do you guys agree? Any other tests I can preform to verify it is a pump before I drop the tank? What else should I replace besides the fuel pump while I've got the tank dropped?

I have had several of the CPI systems, and even though they have one common injector that pressures the poppet valves, vacuum from the intake cycle is required to open each poppet valve. Thus, it is a effectively a simply smart sequential system.
I learned this while trying to clean and test a CPI (spider) poppet valve. I had a mock up of a pressurized system using air pressure regulator and sea foam in the poppet tube. I could not get fuel through any nozzle until I applied air pressure through a venturi creating a vacuum to the exit of the poppet valve. Also sea foam had to be diluted with fuel to exit the nozzle.

Welcome to AF. Good info but look at the date of the last post, this is dead for 4 years.

This is the exact same thing that my 94 4.3w is doing. When I saw this thread I got excited, because I was hoping someone found a remedy to the no start issue. Then to see it wasn't,is quite sad. 2006 lol. Does anyone know this guy personally? To maybe ask him what the prob was. And let the rest of the mechanics out there know. Thanks