Starting Problem With Hot Conditions (1 Viewer)

[farmrjohn]

My son-in-law has a '91 that has been experiencing starting problems with hot weather. He was initially having issues with the EFI relay which seem to have been resolved. The symptoms are in the afternoon on hot days the indicator lights are normal, the engine cranks but won't fire. He's found that if he opens the gas cap, which releases vacuum and shakes the vehicle it will then start and run normally. I have some suspicions on what could be causing this but would like input/suggestions. Thanks, John

 

[CharlieS]

VSV for fuel pressure regulator?

 

[Marco Lau]

Charcoal canister...

 

[farmrjohn]

Thanks for tips-forgot to add this occurs in the afternoon, after work. I was suspecting something along the lines of causing vapor lock.

 

[LandLocked93]

He's found that if he opens the gas cap, which releases vacuum and shakes the vehicle it will then start and run normally.

This suggests that the check valve on the top of the tank is frozen/clogged/rusted shut. There should be no vacuum in the tank. If there is, no air is being drawn into the tank to replaced the fuel consumed, minus the return fuel.
Admittedly it could all be symptomatic of another issue too.

 

[farmrjohn]

Thanks again. Where is the charcoal canister located? I've had a similar issue with other vehicles that had a charcoal canister. Also, where on the fuel tank is the vent? Is the cap itself vented? John

 

[CharlieS]

Charcoal canister in mine (94) is in the front drivers side of the engine bay, aft of the battery.

 

[jonheld]

Thanks again. Where is the charcoal canister located? I've had a similar issue with other vehicles that had a charcoal canister. Also, where on the fuel tank is the vent? Is the cap itself vented? John

The charcoal canister is mounted to the passenger side frame rail.
The tank vents through the charcoal canister.
Other hot starting issues can be caused by a failed fuel pressure regulator.

 

[farmrjohn]

Thanks all, will pass along tips. John