98 C1500 5.7L Fuel Pressure (Won't start)

[BajaScout]

After replacing the intake manifold gasket for the second time, the truck would not start. Thought for sure it was my putting the distributer in wrong. After reviewing the forums, I am sure it is installed correctly. I have spark but no start. Engine cranks over nicely, but acts like it needs fuel. I hooked up a fuel gauge, turned on the key and get 56PSI. Lower than the 60 required. The pressure then slowly goes to 50 PSI. I pinched off the return hose and had the same readings. Pretty sure I need to replace the fuel pump. Is there anything else I need to check. I replaced the fuel pump a couple years ago with a Delphi unit. Maybe this is just a weak link for these trucks. My truck has a little over 100,000 miles on it. Appreciate any advice folks may have.

[j cAT]

you need 60-65 psi. pinching the return line for a short time it should shoot up quite a bit.

the fuel pumps require 1/4 tank of fuel or more to keep cool. running below 1/4 will cause pump failure.

replace relay and filter. replace filter every 30,ooomi.

make sure the ground at the fuel tank frame rail is removed and cleaned.

[BajaScout]

Originally Posted by j cAT

you need 60-65 psi. pinching the return line for a short time it should shoot up quite a bit.

the fuel pumps require 1/4 tank of fuel or more to keep cool. running below 1/4 will cause pump failure.

replace relay and filter. replace filter every 30,ooomi.

make sure the ground at the fuel tank frame rail is removed and cleaned.

Thanks for the info. I did not know about the over heating issue when under 1/4 tank. Won't let that happen again. Plan to get another Delphi as I read they are the best.

[BajaScout]

I replaced the fuel pump with an AC Delco pump. Now I have a steady 63 PSI. Unfortunately the truck still will not start. It cranks over nicely and acts like it is out of gas. I verified that there is spark and that the distributer is pointing to the 8 when the number 1 cylinder is at TDC. Compression is 180 for the highest reading (#7) and 130 on the lowest (#1). At this point I am thinking the camshaft position sensor. Any other thoughts?

[j cAT]

Originally Posted by BajaScout

I replaced the fuel pump with an AC Delco pump. Now I have a steady 63 PSI. Unfortunately the truck still will not start. It cranks over nicely and acts like it is out of gas. I verified that there is spark and that the distributer is pointing to the 8 when the number 1 cylinder is at TDC. Compression is 180 for the highest reading (#7) and 130 on the lowest (#1). At this point I am thinking the camshaft position sensor. Any other thoughts?

you have spark and the proper fuel pressure. spray some fuel in the intake to see if it starts. could be injector wiring /fuses /pcm wiring connector.

possible the timing is off/ spark at the wrong time.

the cps if n/g would provide no spark . with a good signal the PCM commands the spark at the correct time.

TDC rotor should point to #1 cylinder right ?

[BajaScout]

Shot some starting fluid down the throttle body with the accelerator depressed to the floor. Got a backfire and a little flame. I am guessing I still have a timing issue. I noticed in some threads and this web site http://autorepair.about.com/library/a/1a/bl340a.htm that there are two marks on the crankshaft balancer. I only have one mark (groove). It currently aligns with the tab at the top (under the water pump) at TDC on the compression stroke and the rotor points to the number 8 mark on the distributer housing. This mark lines up with the number one contact on the distributer cap. I have a compression gauge hose that I screw into the number one cylinder so I can easily be sure I have pressure to ensure I am on the compression stroke. Wondering why I only have the one mark on the crankshaft balancer? Am I missing something?

[j cAT]

Originally Posted by BajaScout

Shot some starting fluid down the throttle body with the accelerator depressed to the floor. Got a backfire and a little flame. I am guessing I still have a timing issue. I noticed in some threads and this web site http://autorepair.about.com/library/a/1a/bl340a.htm that there are two marks on the crankshaft balancer. I only have one mark (groove). It currently aligns with the tab at the top (under the water pump) at TDC on the compression stroke and the rotor points to the number 8 mark on the distributer housing. This mark lines up with the number one contact on the distributer cap. I have a compression gauge hose that I screw into the number one cylinder so I can easily be sure I have pressure to ensure I am on the compression stroke. Wondering why I only have the one mark on the crankshaft balancer? Am I missing something?

if the crankshaft mark is on the tdc and cylinder One is at the top that seems correct. my guess with the backfire is the distributor is off.

is there fuel in the combustion chamber/plugs ? should be .

[BajaScout]

Not sure how to check there is fuel in the combustion chamber? Two things I am wondering (1) is having one timing mark (groove) on the crankshaft balancer correct, or should there be two? Supposedly with two marks they are 90 degrees out and there are two alignment points. (2) Maybe I should see if I am 180 out and reinstall the distributer there and try it. I am also thinking about pulling the valve cover off the number one side just to be sure I am on the compression stroke (both valves closed).

[j cAT]

Originally Posted by BajaScout

Not sure how to check there is fuel in the combustion chamber? Two things I am wondering (1) is having one timing mark (groove) on the crankshaft balancer correct, or should there be two? Supposedly with two marks they are 90 degrees out and there are two alignment points. (2) Maybe I should see if I am 180 out and reinstall the distributer there and try it. I am also thinking about pulling the valve cover off the number one side just to be sure I am on the compression stroke (both valves closed).

the backfire does indicate the timing being off. 180 out does happen all the time.



when the distributor is removed normal proceedure you do not rotate the engine unless it is required. als mark distributor before removal so install is as close as possible to how it was.

I would try it if you did rotate the engine with distributor out.

when this vehicle cranks and does not start fuel does get dumped into the combustion chambers. some have had to remove plugs and disable the fuel pump then crank engine to blow out the flooded engine.

[BajaScout]

Appreciate the insight. The truck has sat for over a week so if there was any flooding I would think it would have evaporated in that amount of time. Maybe I should pull the plugs and let it sit overnight.

I am 100% certain I have pressure on the number one cylinder when I set the distributor, but so rotating 180 is second guessing myself. I may just go ahead and do it. I found this article and verified the distributor is in correctly:

http://www.gmtruckcentral.com/articles/distributor.html

This is the second time I have done the intake manifold job on this truck No issue starting the truck the first time I did the job. I marked everything, but now I have pulled the distributor several times checking and double checking it is in correctly.

I have 2 distributor caps and rotors, both are used however the symptoms are the same. Maybe I should go ahead and try new ones. Thrown a few parts at the truck already anyways.

Well some more contemplating to do on this one. It is kicking my @$$!.

[Schurkey]

Originally Posted by BajaScout

Shot some starting fluid down the throttle body with the accelerator depressed to the floor. Got a backfire and a little flame.

Was the accelerator on the floor when you CRANKED the engine, or just when spraying the starting fluid?

If the pedal was on the carpet when you cranked the engine, I wouldn't be surprised that you got the backfire and flame out the throttle body.

Originally Posted by BajaScout

at TDC on the compression stroke and the rotor points to the number 8 mark on the distributer housing. This mark lines up with the number one contact on the distributer cap.

Got a photo of that "number 8 mark" on the housing, and how it aligns with the "number one contact on the distributor cap"?

[BajaScout]

Originally Posted by Schurkey

Was the accelerator on the floor when you CRANKED the engine, or just when spraying the starting fluid?

If the pedal was on the carpet when you cranked the engine, I wouldn't be surprised that you got the backfire and flame out the throttle body.

Yes the pedal was to the carpet. Guess that wasn't a smart move? I will try once more by squirting some starting fluid and have the throttle closed to see if it will run for a second or two.


Got a photo of that "number 8 mark" on the housing, and how it aligns with the "number one contact on the distributor cap"?

I will get one. I found both the "6" and the "8" embossed on the distributor. The "8' was harder to find. The rotor does point to the "8" at TDC on the compression stroke. This article helped even though it was for a 6 cylinder it does show where the "8" is stamped:

http://www.automotiveforums.com/vbul...d.php?t=881442

[BajaScout]

Well I let the truck sit for a year and decided I better get it fixed. Still could only find one mark on the balancer but the rotor does point to number one and the small 8 stamped on the distributer with the one mark lined up. Fingers crossed, I will try to get it started tomorrow.

[MT-2500]

Originally Posted by BajaScout

Well I let the truck sit for a year and decided I better get it fixed. Still could only find one mark on the balancer but the rotor does point to number one and the small 8 stamped on the distributer with the one mark lined up. Fingers crossed, I will try to get it started tomorrow.

Put engine TDC no one cylinder and on compression stroke and check for rotor pointing to no 8 on base of dist.

What is engine cranking fuel pressure?
Good hot blue spark to all cylinders?

[Schurkey]

Originally Posted by MT-2500

Good hot blue spark to all cylinders?

A spark-tester is an extremely handy device, and not at all expensive.

$15 will buy one, half that if you're lucky. This is my favorite style, sold by several suppliers under various part numbers. The one with the recessed gap is for HEI ignitions, the other is for points and non-High-Energy electronic (older Chrysler electronic ignition, for example.)

http://www.amazon.com/KD-Tools-2756-...=I7V84Q7FKSUDV

http://www.amazon.com/KD-Tools-2757-...ef=pd_sim_hi_3