1990 R3500 454 crew cab dually need help

[BADAZZ86]

I have a 1990 R3500 crew cab dually with a gm crate 454 that has a no start situation when the engine has ran for more than 15mins. I have replaced ignition coil, spark plugs, wires distributor, cap, distributor, rotor and complete distributor and have no idea what to do now if it sits for 20 minutes it’ll restart but if you run it and then shut it off, it will not restart immediately. you have to wait 20-30 minutes. It’s not the starter because it cranks over just fine just does not start. Will start when the engine is cool or cold just fine. Looking for any assistance with this craziness

[RustyPile]

Welcome, newcomer to our site..

The first thing you need to do is stop throwing parts at it, hoping something will stick. Three things needed for an I/C engine to run -- fuel, air, spark.. Camshaft and valve timing provide the air. So that leaves two items.. Remove any one of the spark plug wires and attach a spark tester.. If you don't have spark, any one of several components could have failed. You've already "shotgunned" most of the spark components but obtain a flow chart for testing for no spark condition.

If you have spark, then the only item left is fuel.. Could be a fuel pump failure, fuel pump relay failure.. Also extremely low oil pressure can cause the fuel pump to shut off.

[BADAZZ86]

I understand what you’re saying all the above items I stated were done as routine maintenance but the coil and distributor were done when the problem arose! The truck has dual tanks and both have new pumps about 2 years ago the truck doesn’t get driven much so in two years I bet it hasn’t seen 600-800 miles. I went through it fromt to back when i got it.
Anyway back to the problem at hand! It ran fine not a problem until about a month ago just a routine cruise out to wash it and stoped at the car wash and this happened get it and just crank away no fire! Sit there trying to figure out how I’m going to get it back home and waiting on a ride and about 30 minutes goes by and bam starts back up drove home fine pulled in the garage shut it off same problem no restart tried again next morning start right up! Has done it multiple times now same situation each time and neither tank work is why I don’t think it’s a pump problem when it happens.

[beasst]

I had a 71 Monte Carlo years ago. Did the exact same thing. Turned out to be the hot battery cable from the battery to the starter was too close to the exhaust manifold and would get hot. Car would not restart for 20 to 30 minutes then would start fine until you shut it off again.
Just a thought

[BADAZZ86]

I will examine that too when yours did that would it crank over just not start? Mine cranks over fast and strong but will not start until whatever is failing cools off

[RustyPile]

Originally Posted by BADAZZ86

I understand what you’re saying all the above items I stated were done as routine maintenance, but the coil and distributor were done when the problem arose! The truck has dual tanks and both have new pumps about 2 years ago the truck doesn’t get driven much so in two years I bet it hasn’t seen 600-800 miles. I went through it front to back when i got it.
Anyway, back to the problem at hand! It ran fine not a problem until about a month ago just a routine cruise out to wash it and stopped at the car wash and this happened get it and just crank away no fire! Sit there trying to figure out how I’m going to get it back home and waiting on a ride and about 30 minutes goes by and bam starts back up drove home fine pulled in the garage shut it off same problem no restart tried again next morning start right up! Has done it multiple times now same situation each time and neither tank work is why I don’t think it’s a pump problem when it happens.

All that typing and nowhere did you say anything about the results of the tests I suggested.. The car wash may or may not have anything to do with the problem. You "THINK" it's not the fuel pump?? How did you come to that conclusion?? Have you actually tested the fuel pressure?? Assume nothing. Just because an item was replaced at some point in the past doesn't eliminate it from the list of suspects.. No one on this forum can walk up to your truck and point to the cause.. They, including me, certainly cannot do that from a computer keyboard.. Systematic troubleshooting is the needed approach.

The troubleshooting flow chart I mentioned can be found in the Factory Service Manual.. If you expect to keep a 35 year old vehicle on the road using your own wits and means, the number 1 tool is that manual..

[BADAZZ86]

The reason I don’t think it’s the fuel pump is one that it has dual tanks with dual pumps and neither work when it dies and it doesn’t stall or lack fuel when it is running only has a restart issue after it is shut off once it reaches operational temperature.

[RustyPile]

Originally Posted by BADAZZ86

The reason I don’t think it’s the fuel pump is one that it has dual tanks with dual pumps and neither work when it dies and it doesn’t stall or lack fuel when it is running only has a restart issue after it is shut off once it reaches operational temperature.

OK, So Here's the step you've taken:

(1) Checked fuel pressure. Found neither fuel pump functions..

Here's the steps you need to take.

(2) Refer to Service Manual for steps and procedures to determine why pumps (both) don't run.. Check fuel pump fuses, relays, and presence of voltage to fuel pump "control system"..

I've already told you that no one, including me, can tell EXACTLY why the engine won't start.. There is a sack full of items involved in the fuel delivery system.. Failure of any one of them can and will cause this problem.. Obtain that flow chart and then come back here if you can't decipher the troubleshooting directions.

[RustyPile]

Go here:

https://www.gmtruckclub.com/threads/...oblem.1472109/

[rdc72]

For what its worth, Ensure your timing is correct as well as the vacuum advance hose is connected, if its off a little it can cause the get hot and no start or very slow start, at least it has for me in the past.

[straight6chevyguy]

Originally Posted by RustyPile

OK, So Here's the step you've taken:

(1) Checked fuel pressure. Found neither fuel pump functions..

Here's the steps you need to take.

(2) Refer to Service Manual for steps and procedures to determine why pumps (both) don't run.. Check fuel pump fuses, relays, and presence of voltage to fuel pump "control system"..

I've already told you that no one, including me, can tell EXACTLY why the engine won't start.. There is a sack full of items involved in the fuel delivery system.. Failure of any one of them can and will cause this problem.. Obtain that flow chart and then come back here if you can't decipher the troubleshooting directions.

Unless I misunderstood I think the op was referring that neither pump or fuel tank would "work" to make it start. I didn't see where he said that the pumps weren't actually working. If I missed something my bad. If op has not checked fuel pressure yet it would be a good idea to do that next.

[Keith Seymore]

Originally Posted by BADAZZ86

I have a 1990 R3500 crew cab dually with a gm crate 454 that has a no start situation when the engine has ran for more than 15mins. I have replaced ignition coil, spark plugs, wires distributor, cap, distributor, rotor and complete distributor and have no idea what to do now if it sits for 20 minutes it’ll restart but if you run it and then shut it off, it will not restart immediately. you have to wait 20-30 minutes. It’s not the starter because it cranks over just fine just does not start. Will start when the engine is cool or cold just fine. Looking for any assistance with this craziness

Still TBI, or converted to carburetor?

During that period when it is acting up will it start (and run) on starter fluid?

K

[wyattglock]

I had a similar problem with my 89 R3500 454. I put new AC Delco pump motors into the sending units. I believe I used the 486 or 386, can't remember which exactly after 12 years.
I also put a Ford solenoid on the fender well, and ran new wire to the starter. With headers, I had a really bad heat soak problem that would cause very similar issues to yours.
After all that, the tank selector switch went bad. If you replace it, make sure you get the switch that stays on.

[Pontiac1976]

Have to agree with rdc72 and or Dist is in correct setting not one or two teeth late or early.

Ensure your timing is correct as well as the vacuum advance hose is connected (A large Vacuum Gauge can help a lot doing tune up timing and timing gun

double check will not hurt

[SCOTI]

I don't think the '90 model TBI engine utilizes vacuum advance. IIRC, the computer is controlling advance.

I'm curious if it's a possible vapor lock related issue? my 89's lines come up the back of the block on the passenger side & were routed close to the exhaust. When I swapped to headers & new exhaust, I slipped some DEI heat shield wrap on the lines where they crossed over the exhaust.

[Pontiac1976]

SCOTI

I don't think the '90 model TBI engine utilizes vacuum advance. IIRC, the computer is controlling advance.

You be right , unless it be switched to carb.

SCOTI you could be right about the vapor lock related issue, but if timing off. That can cause similar problems since he had the Dist. out put new one in. is it bang on or is it off by one or two teeth or + or - any will mess with timing. big Vacuum Gauge really help telling you info.

[SCOTI]

Originally Posted by Pontiac1976

SCOTIYou be right , unless it be switched to carb.

SCOTI you could be right about the vapor lock related issue, but if timing off. That can cause similar problems since he had the Dist. out put new one in. is it bang on or is it off by one or two teeth or + or - any will mess with timing. big Vacuum Gauge really help telling you info.

Agreed.