Fuel pump won’t start when it’s hot outside.

[EarlH]

1993 Chevy Silverado K 1500
Reoccurring problem. Seems when it’s over 95° outside and it sits for an hour or so it won’t start until the temperature comes down. It cranks fine, but no fuel. I’ve replaced the relay. Also, when it is running, it has a funny rough performance shifting out of low gear, especially.

I’m suspecting I have a week fuel pump that is susceptible to high temperatures I know there’s some other issues related to wiring that may be a cause, but I’m leaning towards the fuel pump..

So I think I will replace the fuel pump plus the fuel pump harness.

Is there anyone out there that has experience the same symptoms?
Please respond thank you. I don’t want to go chasing after this issue with just replacing parts and guessing if I can help it. Thank you very much.

 

[Komet]

If you don't want to just replace parts, check your fuel pressure.

 

[EarlH]

If you don't want to just replace parts, check your fuel pressure.

I suspect I can only check the fuel pressure when it starts up again after sitting for a while. Not trying to be difficult, but what fuel pressure should I see and how does that determine if it’s a fuel pump? Thanks for your reply.

 

[Komet]

I suspect I can only check the fuel pressure when it starts up again after sitting for a while. Not trying to be difficult, but what fuel pressure should I see and how does that determine if it’s a fuel pump? Thanks for your reply.

You can check it whenever, put a rag over the first fitting you disconnect to catch the spray. It won't be a colossal amount. TBI wants 9-13psi, if your fuel pump isn't working, you won't see 9-13psi on the gauge. Ideally you'd be checking the pressure at the time when the engine isn't starting. I think TBI needs an adapter deal to check the pressure, might be available as a rental from an auto parts store.

 

[Caman96]

When it’s hot out and it won’t start, can you hear the fuel pump prime? Are you sure the fuel pump harness ground wire has a good clean connection?

 

[EarlH]

When it’s hot out and it won’t start, can you hear the fuel pump prime? Are you sure the fuel pump harness ground wire has a good clean connection?

No, when it’s hot out and this situation occurs it cranks but no fuel pump sound. That’s why I can’t really check the pressure when it’s in this condition but I thought I would try to hook a gauge up to the line coming into the fuel filter when it’s, working to see what pressure I’m seeing. And yes, I’m also going to check the ground on the fuel pump to the frame. I am hoping that it is a little on the loose side and when it gets hot, it just loses its ground. Thank you very much for replying.

 

[Caman96]

When you check for fuel pump priming, you don’t want engine turning over, you’ll never hear it. Turn key to “ON” position “Only” and you should hear the pump prime.

 

[EarlH]

When you check for fuel pump priming, you don’t want engine turning over, you’ll never hear it. Turn key to “ON” position “Only” and you should hear the pump prime.

Thank you for the info. I haven’t had a chance to test the fuel pressure yet, but I do have another question for everyone. It was a fairly cool day the other day and I took it out to do a couple errands not fearing the failure of the hot weather preventing me from restarting. It started OK, but it seemed did not run very well, especially shifting through the gears hard shifting. My question is …is this a further example of a failing fuel pump not providing enough fuel pressure for proper shifting.?

 

[GoToGuy]

If you have low fuel pressure, you'll have will have inadequate or erratic fuel injection spray. Results in poor , crap running, so your gonna have a hard time RPM , accel and shifting.
Harbor freight , or Amazon has fuel injection test kit includes test adapter for GM TBI injection.