95 blazer fuel issues

[wolfox]

Have you verified that you've lost pressure yet with the proper gague? Remember far back into your High School chemistry - remember your "fire triangle"? To have ignition of *anything* you need fuel, ignition source and oxygen. Check your fuel pressures, check filter and proper throttle operation and make sure that you have a good, strong blue spark at the plugs. If you have all three, then we need to start looking elsewhere.

[Jon Teeter]

Hey guys just thought I would let you know unfournately I havn't got a chance this weekend to drop my tank because of the fact that it hasn't stopped snowing. I planned on taking it to my buddies house so I could use his garage but with the poor road conditions I dont want to chance it because I can barely keep it running. I will keep you guys up to date though as I plan to change the pump,strainer,and pulsator. Also is it possible to cyphen out the 18 or so gallons of gas in my tank or do you think I could use a couple floor jacks maybe to drop the tank?

[blazee]

I'd disconnect the line at the filter, and put a gas can there, so that the fuel pump would pump out the gas.

[Jon Teeter]

Just to keep you up to speed I finally dropped my tank today.Unable to get the gas out it was not fun doing by myself but its out.I did disconnect the line to the filter and turn the key but all I got was one little shot of gas so I kinda knew then it was definetly the pump because I heard it running but no gas was coming out.I also discovered I need a new sending unit now because where the float attaches its broke.Guess that explains why the fuel gauge wasnt registering right.Due to the extra cost involved now it may be a little while untill I let you know for sure this was the problem.

[wolfox]

I just got through with changing my fuel pump today. THe Bosch replacement is a godsend - that turbine pump is *quiet* and certainly develops the right pressure and flow rates. In a nutshell:

WHen you drop the tank, try to get it as dry as possible. I did this with a limping fuel pump by using the pressure relief valve on the fuel pressure gage and bypassing fuel flow as the engine was idling to a huge gas tank.

When you drop all of the body armor off, you may have to use WD-40 or some other penetrating lube to free up the long 15mm bolt that holds the rear strap to the truck. I had to hit both that one, and the 15mm nut for the front strap.

Loosening and removing your filler neck bolts just inside the gas flap will give you more play room to line up and take off/reinstall the filler and vent lines at the back of the tank.

USE a set of flare nut wrenches and a back-wrench on the crimped fuel lines to remove the main fuel line and return to the tank. Feel atround on the top of the tank closer to the outside of the truck around where the sending unit's retaining collar is. You'll fine a fuel vapor relief valve with a pressed on fuel tube. Remove this tube in addition to the grounding strap and disconnect the wire harness for the sending unit before you completely remove the 15mm bolt to drop the rear of the tank.

Loosen, but do not completely remove the front 15mm nut to drop the tank down a good 1.5-2 inches and reach around the front of it through the plastic body armor wrapped around it. Near the front, outside area you're going to find another vapor purge valve. Remove the tube from the valve or the metal riser tube that meets up here. I broke the front one, not knowing it was there and had to go to the dealer to get the replacement valve. Thew new valve went in easy, but breaking the crud and grit around the old one was a PITA.

*CLEAN* the top of your tank once it is down. For some god awful reason there was like 10 pounds of kitty-litter like gravel, rocks and compacted mud and road grit solidified like terra cotta clay all atop of my tank. I could not even see the collar from the retainer that holds the sending unit in the tank through the grime. WD-40, brushes and plenty of towels are your friend.

I do not know if they ship from the factory like this, but some yo-yo gooped the top of the sending unit shut with what looked like JB Weld. Took me *HOURS* of clean-up and chipping at this crap to get all shiny looking metal and finally get the ring to rotate after pounding the lock tabs flat with a screwdriver tip and taps with a hammer.

Remove the retaining ring carefully out from around the sending unit's pipes and wire harness. Once free, the sending unit simply comes up and out of the tank. As you withdraw it from the tank, be mindful of the bends in the pipes and the sending unit float. Mine came out with a nice, gentle, up, to the side, and 180 degree twist in one fluid motion to get the works out of the tank in one go.

The old fuel pump literally pops out of place. Use the fresh grommet for the pump base in the Bosh kit to replace the bayonet-fitted OEM pad. Remove the pulsator unit, it's not needed with a turbine pump. Replace the pulsator unit with the small length of rubber fuel line in the Bosch kit. Insert the new motor into it's rubber sleeve until the base metal of the body projects slightly from the bottom of the pump from under that sleeve. Use the new pressure clamps that came in the kit to secure the pump and fuel line that replaces the pulsator to the sending unit assembly. Once tight, give them a good squeeze with horizontal pliers. THis crimps them *solid* into place. Use the upgraded wire harness in the kit to complete the electrical conection from the pump motor to the old wire harness' clip where the old motor hooked up. It will look a little long and gangly when done, but nylon ties will tidy things up. Double check that the sending unit's pipes are true and straight, and that the pump sits SQUARELY in the grommet bore, the grommet itself pressed snugly against the lower metal clamp that retains it to the sender. Pop your new strainer sock onto the end of the pump in the same manner that the old one was oriented. It will press onto the end of the pump with a firm pressure and a small click. My replacement was slightly oversized from the stock, OEM part. But it is still more than manageable to set properly back into the tank if you angle it in, and reverse the motions I described above.... in this case, one side of the filter goes in after letting the float into the tank first. Rotate to the other side gently to poke the other side of the filter into the thank. Rotate 180 degrees as you lower it, watching the angle of the tubes. The tangs at the tp of the sending Unit will not let you put it in any other way. Now about that tank gasket - which you do before you drop the sending unit...

Clean, clean, and clean again the lip of the tank where the sending unit goes. DIscard the old tank seal and use the new one in your kit. If you get the same kit I did, posted earlier; you will find two gaskets. The smaller one is what you want. I lubed the gasket with a thin layer of plain old oil to aid assembly and assure that it would not be pinched/displaced when I tap the locking collar's ring in the opposite direction to seal the tank again. Once the locking collar rotates back into place, pry up on the ears of the tabs you tapped flat earlier to lock it securely into place.

The rest of the job is pretty much the reversal of dragging the tank down. However, you'll have to be either a midget or have vice-grips for hands to finesse the filler neck tube and vent line back together. It took me a few tries and the gentle persuation with the tip of a very thin phillips screwdriver, but I got them back into place. Once the tank was bolted snug, but not totally tight within the straps, the tubes mated with the hoses perfectly. I then re-installed the the three 7mm bolts inside the filler neck to help hold that just where I wanted everything and finished tightening up the straps.

Good luck, and I hope that you all glean something from my paltry contribution. I unfortunately did not take photographs...I was not about to go and get my expensive digital cam get all covered in grease and grit.

The real thrill now:

On a truck that was sitting on a battery for two weeks (It was disconnected before I began work), I hooked up my fuel pressure gage. I dumped about 10 gallons of gas in the tank for a little over half a tank. I hooked that battery up, and turned the key to "RUN" but didn't start it. THe fuel pressure gague *immediately* jumped up to 62 PSI. I took the key out, and it dropped....too quickly. I thought I goofed something up. So I am looking for pooling gas, sniffing for it, nothing. Must have just been a ton of air in the system rushing past the fuel regulator. I repeated the KOEO two more times. At the third time I turned the key, she held at 64 PSI, and maintained that pressure unassisted for at least 30 minutes as I picked up, counted tools and got everything out from under the truck and dropped it off the jackstands.

I merely touched the key and she lit up hard and strong, not even half a crank. I was getting used to having to wiggle the key back and forth a few times only to get a weak and sputtering start and a surging, bumpy idle. *ROCK SOLID* smooth idle and instant, lunging starts are the norm again.

Cleaned up and went for a test drive.... I came back home before I was cited for exhibitionism or a speeding ticket. She's got power like I never felt before, I guess fuel flow is where it belongs again. She does not struggle to make power, and can easily navigate the hills on the highway without dropping out of overdrive like she was doing in the weeks leading up to the pump failure. My baby's BACK!

[Rick Norwood]

Wolfox, In your post you said you can remove the pulsator unit and replace it with the short piece of rubber fuel line from the kit. When I did my '93 fuel pump, I didn't know what the chambered piece was that connected to the top (discharge side) of the pump. I was also led to believe that these kits are "universal kits" that probably fit various different models and years. So when I installed the new Bosch pump, I installed it back into the pulsating unit just like the old one came out. My neighbor had just replaced the pump in his 88 Chevy Van and it didn't have a pulsating unit, so he had to replace the short piece of fuel line with the new one from the kit. When I finally started my truck, it started on the first try and ran fine. I immediately went to the gas station and filled up to check for leaks, and the only thing that happened after I filled up was the engine seemed to cough twice, which I assume was air in the system, and has run fine ever since. So my question is, Did I screw up by leaving the pulsating unit in the system?

If you still have the old pulsating unit could you please post a picture of it so others will know what we're talking about?

Thanks - Rick

[wolfox]

I took three high resolution shots of it on my desk - to find that my compact flash to USB gizmo took a dump. I tried taking photos of it with the webcam, but the ambient light is no good, looks fuzzy and indistinct. Let me see what I can post from work tomorrow, if I can; otherwise it will have to wait until I pick up a new CF -> USB drive. However, the long and the short of it here, the pulsator unit looks like a brass cap and two small bellows attached to a plastic body. Over this body a clip is pressure fitted to hold a pair of orange rubber grommets that the fuel passes through from the top of the pump to the main fuel line. You didn't screw up so much as left a part in the tank that was just as old and prone to failure. Updated, Bosch style turbine pumps provide a steady stream of fuel as opposed to older georotor or roller-cell type fuel pumps that provide fuel in high speed pulses. Output from a turbine is smooth, consistent and high volume + pressure. The little black high pressure fuel line that came in the Bosch kit replaces the bulbous, brass and plastic press-fit pulsator unit for these very reasons. Over time the seals harden and degrade in the pulsator unit and leak fuel within the tank under pressure, robbing your top-end pressure a bit. Mine's a little brittle and dried looking. My fuel pump still worked too, but at "weak" pressure. Testing it outside of the tank using a very light hydraulic oil says "OK". The pump develops full pressure again...go figure. I'm keeping it to see if I can recycle it into a high pressure oil pump @ slightly reduced volume to run an experimental gas turbine.

Oh, and do not kid yourself, the AC-Delco and Delphi "OE" parts are cheaper knock-offs of Bosch products. Bosch *defined* the technology back in the day and is still a product leader when it comes to fuel injection parts. The kit I picked up is what the truck *should have left the factory floor with* in the first place. The part number I qoted earlier for a 4x4 4-door VIN W Blazer built in '95 is nearly a dead match. The only two variances was a slightly heavier constructed wiring harness that required a kit supplied adaptor to hook into the existing harness. The other was the exclusion of a pulsator, being a totally different pump design that just doesn't need it.

EDIT: Here are the pictures:

The back of it is made of brass and the expansion bellows:



Here is an oblique view with the plastic side up and showing one of the rubber grommets inside:



Here it is against a standard, full size zippo for scale, it's not a big part at all.

[Jon Teeter]

NOOOOOOOOOOOOOOOOOOOOOOO
Just got done replacing fuel pump and sending unit.NOTHING!! God help me.Its doing the same thing .I looked for a kinked line or a leak NOTHING.New bosch pump runs yes it is quiet ,and the fuel gauge works now.A couple positives ,but this didnt solve my problem.What else could it be?New pump new fuel filter new strainer new sending unit and still NO pressure. I spent over $250 just for the fuel gauge to work I guess.HELP PLEASE

[Rick Norwood]

Wolfox, Thanks for the pic's, next time I think I'll pay closer attention to the printed directions that come with the kit. That is exactly the part that I was talking about. So far so good, the truck runs fine.

Jon, In your very first thread, you said you had narrowed it down to a fuel issue, No pressure in the fuel rail. You said the new pump runs, but you have no pressure now? Do you get fuel at least to the filter? Try disconnecting the fuel filter and turning on the key for a second (with something under the fuel line to catch the fuel, of course. A clean 2 liter pop bottle works pretty good.) If you got fuel to the filter, but not to the fuel rail. I think you could have a fuel line blockage. If you don't have fuel to the filter, it could be possible that something popped off inside the tank. Did you attach the new pump with the short piece of fuel line and clamps in the kit? (I ask this because I didn't on my 93. It didn't replace my Pulsator unit and the old pump didn't have clamps to start with, so I didn't really have a place to put them on.)

Do you have spark? Give us any thing else you have seen or heard. Have you done any other work to the truck? Check your Distributor cap, wires etc. Any trouble starting more when the engine was hot or cold? (I'm thinking Ignition Module, I think the 95's still have the one inside the Distributor.)

[Rick Norwood]

Well I guess all good things must come to an end. In Arizona we have an emissions test that includes among other things, a fuel tank pressure test. The tank has to be able to hold 10 Lbs. of pressure. Well, in short, mine failed. I haven't had a chance to look into it yet, but it looks like the tank might need to come down.

When I re-assembled the tank with the new rubber O-ring that came with the kit, it went together real easy. The assembly fit right into the groove and the Clamping Ring tapped around and locked real easy.

I'm wondering if was too easy.

Here's my question, Has anyone had any experience with these O-rings not sealing properly? When I filled the tank with gas, there were no leaks. Not even a drop that I could see, but it won't pass the pressure test.

[Jon Teeter]

Hey guys I'll get you up to date in a minute with my situation, but first this is for Rick. Did you use a new O ring or the old one? I'm asking because when I went to put my sending unit back in I noticed the O ring that came with my new pump was a tad too small(It came with two neither of them were the right size).Luckly the one that came with my new sending unit was the same size as the old one.The sending unit seems to have been a waste of money too because I drove my blazer to my buddies house today to use his garage and now the fuel gauge moves back and forth a little bit.As for the rest of the story.When I got to his house I used his fuel gauge to check my pressure and looks like its not an issue anymore.When I hit the key it goes right to about 61psi.When I start it and let it run it stays at 58psi or so and just like it should if I hit the throttle it jumps right up to 62.This was all good except its still running the same as before.It barely idles on its own.When your driving and giving it gas its fine but slow down at a stop sign and it wants to shut down unless i give it gas.Im really confused how this started with me having no fuel pressure when it first started running this way and now I seemed to fix the problem but yet I still have the original problem.I also still have good spark. I tested the TPS today it was good and Im going to try to clean the EGR tomorrow or as soon as I get a chance.

[Rick Norwood]

Jon, I think you are exactly right. I used the new O-Ring that came in the box with the Bosch Pump. The old original one was cracked and dry rotted. I suspected then and still contend that the new O-Ring is slightly smaller in thickness and does not have the same "Pinch" as the original. That is why I think it went together so easily. I am certain that the new O-Ring will prevent gas leaks but it will not hold 10 lbs. of pressure. My plan is to drop the tank this Saturday and replace the O-Ring with a new one from the dealer. The dealer described the one he had in stock and it sounds like the one that I took out. The one that I took out had three small tabs on it to help hold it in place. The Bosch one was a simple O-Ring. I will report back when I'm Done, but I would certainly caution anyone doing a fuel pump to pay close attention to the O-Rings and make sure you are not setting yourself up for a repeat drop-the-tank-performance. What makes this ugly is I'm am trying to sell this truck and the new owner will not be able to transfer the title until the truck passes emissions.

[JoulesWinfield]

Wow, great thread guys.

My little contribution - @Jon, it seems like youre describing the EGR problem I had with mine. Hardly idles but seems to run pretty well. I had a good size chunk of carbon holding my EGR open. This was after a long drive on the highway pulling a trailer. They said this is likely at high rpms.

Also reguarding the pulser, I had a 1996 Sierra 5.7L. When I replaced the pump, dont remember what brand, I put the pulser back on. It ran great. Then a couple days later on the highway it died. The damn pulser fell off. So I had it towed home and replaced the pulser with the little tube. Didnt notice any performance difference with either combination.

Lastly is everyone replaceing their fuel filter regularly?

Oh, almost forgot, to remove the fuel from the tank check this out http://www.parkeryamaha.com/index.as...D&ProdID=17542. Works like a charm. I just used a couple of very clean five gallon buckets and changed my fuel filter like two or three days after the job. (Two or three days was like two tanks of gas back then.)

[Jon Teeter]

BINGO
I took my EGR valve off yesterday and cleaned it real good.That was it.Unreal that my fuel pump went bad and this all at the same time but Its fixed now.Thanks alot for all the help guys I really appreciate everyone trying to help me out and I hope maybe I can do the same for somebody else in the future.The only bad thing about my fix is the fact that somehow the threads on the one side where the EGR mounts were destroyed .That blew my mind because the bolt came out very easily and went back in a few turns the same.When it started resisting I looked with a flash light and half way back the threads in the manifold were desrtoyed.I dont know what happened I didnt force the bolt I guess its just that aluminum is touchy but I plan on trying to retap it soon as I get a chance.For now I just slipped a 3/8 nut on the bolt as a spacer which worked as a good temporary fix.Thanks again Everyone.If I wouldn't have found this site my blazer would be sitting in the driveway with busted out windows and size 13 dents allover it.

[BlazerLT]

Whoa now, why is no one telling him to check out his fuel pressure regulator on the CPI injector?

No pressure, regulator shot.

The pump is running.