I have a 87 R10 TBI 350 long crank time after sitting hours.

[lehman368]

It has a long cranking to start at least 4 seconds then fires up. You stop and shut off run in some where for 15-30 minutes it fires right up after turning the key. Is this normal with the early tbi models? Thanks for any help.


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[VileZambonie]

No it's not normal. Check your fuel pressure, check for a leaking injector, ensure fuel pump energizes to full pressure with initial key on cycle.

[Irish_Alley]

vile would this be symptomatic of a bad fuel pump relay?

[zieg85]

My cousins 90 does this.  If he cycles the fuel pump twice before cranking it starts up pretty quick.  Other than that it will crank for longer than it should.  Runs great otherwise and it has a fairly new fuel pump as he thought that was the problem.

[Stewart G Griffin]

1) First, i assume you mean sitting for hours, not the other thing that was typed.......

i'm going to go with leaking injectors.

[lehman368]

No it's not normal. Check your fuel pressure, check for a leaking injector, ensure fuel pump energizes to full pressure with initial key on cycle.

I can cycle the key on and off a couple of times dose not seem to help. The throttle body was rebuilt with new fuel injections last year



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[lehman368]

1) First, i assume you mean sitting for hours, not the other thing that was typed.......

i'm going to go with leaking injectors.

The injectors was replaced just last year and tbi was all rebuilt.


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[Irish_Alley]

do you hear the fuel pump come one when you first turn the key on?

[lehman368]

do you hear the fuel pump come one when you first turn the key on?

It not real loud but I can hear what seams like a fuel pump it has duel tanks it’s the same on both fuel filter was changed also when we rebuilt the tbi. Each tank would have it own fuel pump correct.


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[lehman368]

do you hear the fuel pump come one when you first turn the key on?

It not real loud but I can hear what seams like a fuel pump it has duel tanks it’s the same on both fuel filter was changed also when we rebuilt the tbi. Each tank would have it own fuel pump correct.


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Do you know if there is a check valve on the return line to fuel tank or where a check valve would be located at?


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[Irish_Alley]

no, theres no check valve. if you take the fuel cap off you should be able to hear the fuel pump for a few seconds when the key is first turned on.

[lehman368]

no, theres no check valve. if you take the fuel cap off you should be able to hear the fuel pump for a few seconds when the key is first turned on.

Ok I will check that thanks


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[MIKE S]

First of all it just a guessing game if you don't have a fuel pressure gauge on this. If you can get a hold of a gauge you can isolate the fuel pressure drop of either the supply side or the return side. If you cant get a hold of a gauge and see no external leaks or drips from the injectors it could be the pump check valve. But if does it on either tank its not likely. I know you said the TBI unit was rebuilt but my best guess would be the fuel pressure diaphragm seat. They are a highly polished seat that mates to the casting in the throttle body to close off the fuel return to the tank. If it is not seating good from say a burr it could be bleeding off.

[Irish_Alley]

i was recently working on a tbi from the 88-98 style, pretty much the same setup. i installed a pressure gauge where the filter should be and installed two ball valves, one on each side. this way i could turn off each side to check to a check valve and there was none on either side, pressure bleed off from both sides. problem was either a poor ground or bad fuel. changed batteries and the issue slowly went away. but there was still no pressure being held, like there was no check valve

[lehman368]

First of all it just a guessing game if you don't have a fuel pressure gauge on this. If you can get a hold of a gauge you can isolate the fuel pressure drop of either the supply side or the return side. If you cant get a hold of a gauge and see no external leaks or drips from the injectors it could be the pump check valve. But if does it on either tank its not likely. I know you said the TBI unit was rebuilt but my best guess would be the fuel pressure diaphragm seat. They are a highly polished seat that mates to the casting in the throttle body to close off the fuel return to the tank. If it is not seating good from say a burr it could be bleeding off.

I working on getting a fuel pressure gage. I just got the 87 Series trucks service manual and drive  ability books. Im seeing there are two types of fuel systems and where to put the the pressure gage by fuel filter. I’m been getting everything by one most of the other issues corrected but this long cranking issue has been around for 3 years as long as I have owned the truck. But I will get pressure gage and start there. I’m going on vacation tomorrow for a week so it will be a little bit before I get under the truck. Thanks for the information I will keep you All  posted on what I find with fuel pump and pressure


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