92 S10 W Blazer 4WD Fuel trouble

This is old type much-discussed trouble. If its already been posted I would appreciate a link to it! ;-) I did find many discussions but not the exact trouble I have...

This '92 CPI 'W' 6 cyl sat for about a year and a half with the fuel tank full under a carport. It ran fine when I parked it. The plates expired from Alaska and I waited till I got it here (Missouri). I had to put in a new battery. It started up instantly and ran fine. I had planned to replace dist. cap and rotor before I quit using it. I had the parts when I quit using it, but didn't change them till now. I changed those, started it up after and it ran fine. Shut it off and the next time I attempted to start it would not fire a lick. I checked spark and it is good. Checked fuel pressure and it was 45 lbs. cranking and holds when not cranking. I had replaced the pump about 18,000 miles ago...!* drat. So I went and bought a new one at the parts store. Checked the pressure again before taking it apart. Had 50 lbs and it started and ran fine. Checked it a few more times and got 54 lbs running and jumps up to 64 when the gas pedal is 'goosed'. Waited till the next day and it would not start, pressure at 48 lbs cranking. Starts and runs fine if primed with a little fuel. Powers up hills easy and is very 'peppy'. No black smoke out of tailpipe. Do you think its possible the regulator is flaky? The poppets and associated parts were replaced by a WA. shop, (I was not in WA. state at the time about 15,000 miles ago) I don't know what was replaced, but it cost $500.

This is old type much-discussed trouble. If its already been posted I would appreciate a link to it! ;-) I did find many discussions but not the exact trouble I have...

This '92 CPI 'W' 6 cyl sat for about a year and a half with the fuel tank full under a carport. It ran fine when I parked it. The plates expired from Alaska and I waited till I got it here (Missouri). I had to put in a new battery. It started up instantly and ran fine. I had planned to replace dist. cap and rotor before I quit using it. I had the parts when I quit using it, but didn't change them till now. I changed those, started it up after and it ran fine. Shut it off and the next time I attempted to start it would not fire a lick. I checked spark and it is good. Checked fuel pressure and it was 45 lbs. cranking and holds when not cranking. I had replaced the pump about 18,000 miles ago...!* drat. So I went and bought a new one at the parts store. Checked the pressure again before taking it apart. Had 50 lbs and it started and ran fine. Checked it a few more times and got 54 lbs running and jumps up to 64 when the gas pedal is 'goosed'. Waited till the next day and it would not start, pressure at 48 lbs cranking. Starts and runs fine if primed with a little fuel. Powers up hills easy and is very 'peppy'. No black smoke out of tailpipe. Do you think its possible the regulator is flaky? The poppets and associated parts were replaced by a WA. shop, (I was not in WA. state at the time about 15,000 miles ago) I don't know what was replaced, but it cost $500.

Specs are 54-64 lbs fuel pressure.
You need around 62 lbs pressure engine cranking on a cold start for injectors to squirt.
Run a full fuel presure check.
Engine cranking cold presure?
Engine running on road pressure?
Check for fast leak down pressure?
Block return line and check full fuel pressure?\
Check fuel direct pressure into fuel filter in line?
Good fuel pump should be up over 90 lbs direct pressure.

I tested pressure before fuel filter on frame, 52 lbs max. (35 first key on pump run, then 52 after 2 more runs) I don't know how it had 60 lbs on a different day. It seems to change the output pressure on its own whim. I think I'll run a couple tanks of gas thru and then replace if it continues to be unstable. - sure didn't get many miles out of that pump.

I tested pressure before fuel filter on frame, 52 lbs max. (35 first key on pump run, then 52 after 2 more runs) I don't know how it had 60 lbs on a different day. It seems to change the output pressure on its own whim. I think I'll run a couple tanks of gas thru and then replace if it continues to be unstable. - sure didn't get many miles out of that pump.

There is leakage some place or fuelpressure regulator is bypassing or fuel plump is weak.

You need to block return and check to see if pressue comes up to 75 lbs or more
If so regulator is bypassing.
and\
And then check fuel pump direct pressure.
If direct pressure is under 80-85 lbs fuel pump is weak
Give us them readings and then we can help.

The pump is bad, the last test into the gauge attached on line before the filter would not reach the minimum pressure. (Output of pump dead ended into gauge.) Barely reached 52 lbs. - I don't know how it read 64 pounds when punched and running. The readings seem to be all over the spectrum on different days. It does not leak down though, neither when all connected or just the pump to the gauge. It runs fine when it starts, even if 'priming' with a little fuel in the manifold was necessary. Thanks for all the help!

If pump is getting good 12 volts and good ground and wiring to it is good.
Time for a new delphi pump.
Do not let them sell you a Airtex or aftermarket junk pump.
God luck and let us know how it goes.

I put the Airtex pump in a bucket with the filter on and connected a gauge via rubber hose and clamp. put fuel in the bucket and applied power to the pump. It ran up to 100 psi instantly and the built-in bypass kicked open. It gradually leaked off the pressure down to about 60 psi over 20 minutes or so. Though that would run the engine fine, I returned it to the auto parts store in town (I live on a farm) and they took it back, then ordered a Delphi unit that should be here tomorrow. Only a few bucks more... quite a bit more than the internet, but way more easy to get swapped if it gives trouble. I'll measure the Delphi pump before I put it in and post the results just FYI.

I put the Airtex pump in a bucket with the filter on and connected a gauge via rubber hose and clamp. put fuel in the bucket and applied power to the pump. It ran up to 100 psi instantly and the built-in bypass kicked open. It gradually leaked off the pressure down to about 60 psi over 20 minutes or so. Though that would run the engine fine, I returned it to the auto parts store in town (I live on a farm) and they took it back, then ordered a Delphi unit that should be here tomorrow. Only a few bucks more... quite a bit more than the internet, but way more easy to get swapped if it gives trouble. I'll measure the Delphi pump before I put it in and post the results just FYI.

The full pressure test was good on the Airtex.

But trouble with Airtex pumps they have a high fail rate and many are weak on the pressure end.
For some reason parts places insist on pushing the junk Airtex pumps when they know they are bound to fail.
They must make more money selling them than the Delphi.:sarcasm1:
Or have a warehouse full of them they are trying to unload.

Carquest is the only one I know of that has dropped airtex like a hot spud.

Good Luck and let us know how it goes.

Well.... here is an update. I returned the Airtex pump and ordered a Delphi. I put that in, but tested with it in the tank. Connected the gauge before the fuel filter. It went up to 84 lbs. max and leaked down to 66 after five minutes on the second try. 1st try went down to 55lbs. So I put the tank up in its spot under the rig and noticed a wet spot on the seam in back. Drat. Took it back out and epoxy was applied. Next day I installed the tank and started the engine just fine. Drove it a couple hundred miles over the last several days, today (Sat.) it stuttered and almost died at a stop. I managed to keep it running to a job I had. Shut it off and looked under the hood - didn't see anything unusual. * Went in, got some tools and started to drive to nearby building. Would not start. Just crank. Key off / on 6 times - no start. Pushed the pedal to the metal and held the starter engaged, it stuttered and gradually picked up speed and ran the block to the next site. (a little rough idle) I quit early and drove it home, checked the fuel pressure at the test port on the engine. 63lbs - holds at 61 after 5 minutes. Engine starts and runs fine sitting here. Fuel pump sometimes makes a rattling noise for part or all of its cycle when key turned on and not cranked. Not all the time. Can not hear if it does the rattle when the engine is running - too much other racket. Runs with 52 - 53lbs at idle jumps to 63 when 'goosed' . Its just perfect. Now. I can just see myself stranded on the way to a job. Not Good! I wonder do they make electrical sending units for gas pressure gauge to install permanent? I think I need to monitor the pressure while using the rig but don't like the idea of a fuel filled line that could leak.

Well.... here is an update. I returned the Airtex pump and ordered a Delphi. I put that in, but tested with it in the tank. Connected the gauge before the fuel filter. It went up to 84 lbs. max and leaked down to 66 after five minutes on the second try. 1st try went down to 55lbs. So I put the tank up in its spot under the rig and noticed a wet spot on the seam in back. Drat. Took it back out and epoxy was applied. Next day I installed the tank and started the engine just fine. Drove it a couple hundred miles over the last several days, today (Sat.) it stuttered and almost died at a stop. I managed to keep it running to a job I had. Shut it off and looked under the hood - didn't see anything unusual. * Went in, got some tools and started to drive to nearby building. Would not start. Just crank. Key off / on 6 times - no start. Pushed the pedal to the metal and held the starter engaged, it stuttered and gradually picked up speed and ran the block to the next site. (a little rough idle) I quit early and drove it home, checked the fuel pressure at the test port on the engine. 63lbs - holds at 61 after 5 minutes. Engine starts and runs fine sitting here. Fuel pump sometimes makes a rattling noise for part or all of its cycle when key turned on and not cranked. Not all the time. Can not hear if it does the rattle when the engine is running - too much other racket. Runs with 52 - 53lbs at idle jumps to 63 when 'goosed' . Its just perfect. Now. I can just see myself stranded on the way to a job. Not Good! I wonder do they make electrical sending units for gas pressure gauge to install permanent? I think I need to monitor the pressure while using the rig but don't like the idea of a fuel filled line that could leak.

No electrical pressure gauges I know of.
You need to get a pressure reading when it acts up.
Best to tape a fuel pressure gauge to outside windshield or or outside mirrow.
Always keep it outside cab in case of leakage.

And also watch power and ground to fuel pump.
And when it quits or acts check for lose of spark.

Any codes or check engine lights?

No electrical pressure gauges I know of.
You need to get a pressure reading when it acts up.
Best to tape a fuel pressure gauge to outside windshield or or outside mirrow.
Always keep it outside cab in case of leakage.

And also watch power and ground to fuel pump.
And when it quits or acts check for lose of spark.

Any codes or check engine lights?

No electrical pressure gauges I know of.
You need to get a pressure reading when it acts up.
Best to tape a fuel pressure gauge to outside windshield or or outside mirrow.
Always keep it outside cab in case of leakage.

And also watch power and ground to fuel pump.
And when it quits or acts check for lose of spark.

Any codes or check engine lights?

If holding the gas pedal to the floor helped it sounds like the engine is flooded. This is usually caused by the spider assembly leaking in the intake manifold. When you hold the gas pedal to the floor the PCM puts the fuel system into "clear flood mode" and shuts off the gas. Take the upper intake off and see if it is all washed out from leaking gas.

Hey! I found what looks like a good source for gauges - glowshiftdirect.com 100 lb fuel pressure gauge is $45 for the cheepest. I checked it this AM and a couple times during the day. Starts and runs great. Pressure is where its supposed to be. I didn't think to turn around and look for black smoke... when it almost died at the stop I checked the mirrors and did not notice any then. When it acts up again I'll remember to check. The check engine light came on during the drive home and then went off again before I got there. I'm not sure on this rig how to check an engine code - I'll have to find out what pins to short and how many flashes mean what, if that how its done on this one. I have a computer test program for 96 and later years but no help on this '92.

Hey! I found what looks like a good source for gauges - glowshiftdirect.com 100 lb fuel pressure gauge is $45 for the cheepest. I checked it this AM and a couple times during the day. Starts and runs great. Pressure is where its supposed to be. I didn't think to turn around and look for black smoke... when it almost died at the stop I checked the mirrors and did not notice any then. When it acts up again I'll remember to check. The check engine light came on during the drive home and then went off again before I got there. I'm not sure on this rig how to check an engine code - I'll have to find out what pins to short and how many flashes mean what, if that how its done on this one. I have a computer test program for 96 and later years but no help on this '92.

Ground pins A and B for codes check.
If check engine light is not on it will not have codes.
And code check may not show history codes.
Only a good scanner will show history code.

Hmmm, well it won't do me any good to check codes if I can't get history...! I drove it 80 miles to the store and back and it ran just like new... No check light. Stop and start at several places and no problems. I hate it when they aren't broke all the time... back window rattles though, I forgot about that annoyance... been so long since I drove it.