1989 Chevy farm pickup ????

Hi all,
Last week I hauled some cattle to market on the hottest day this year in Southern Minnesota. It was 100 degrees with about 40-50 SE wind. I made it home ok, problem is when I went to start the pickup again, it started and ran about 1 minute and killed. It acts like it is not getting any fuel. I took the gas cap off because it was vapor locked. I thought it would start with the gas cap off, but no luck. This is an early model of EFI in the Chevy trucks. It is a 1989 Silverado 3/4 4x4 with the 5.7L 350cu gas engine. I am wondering if the fuel pump is shot. The truck turns over fine, it just doesn't seem to want to fire at all. Yes it has 3/4 tank of fuel in it. Does this truck have an internal fuel pump in the gas tank? Just throwing out ideas. Looking for any and all advice. Thank you.
Kow Farmer

yes it is most likely the fuel pump. they can go just like that. just expirenced the same problem with my skid steer am]nd it has happpened in my ford explorer.

did you check it for spark

Had a 90 with the 350 - it had the internal fuel pump. When the fuel pump went on it, it was acting like it had no power. Took a couple days though before it just about quit.
Overall a great truck. Miss that truck...

I agree, check for spark first. Ignition modules go bad more often than fuel pumps. Had symptoms like that in a '90 GMC, acted like fuel problems, turned out to be ignition.

Also agree on the spark issue although I did replace the in tank fuel pump as well. I still miss my 89 3/4 ton It was the toughest,straightest driving fuel hungry vehicle I ever drove. It had about 500,00km on it when I finally let it go after 19 years. "Upgraded" to a 98 3/4 ton diesel so far so good.

Fuel pump is in the tank on this truck. There is also a fuel pump relay on the firewall. When you turn the key on, fuel pump should run for two seconds. Can you here the fuel pump with the key on?? You didn't mention what transmission, but if it has the TH400 it also has a relay on the firewall and I believe it is the same as the fuel pump relay, so you could try switching the two and see if that makes a difference.

Also, TBI fuel injectors only spray when engine is cranking. Maybe you could have an assistant to turn over engine while watching for injectors to spray fuel. If the pump runs and fuel sprays while cranking, my guess is the ignition module is bad, as that is very common on those trucks.

If you do not have fuel at the TBI, I would try turning engine over and pouring a little gas down the throttle body to see if it fires. If engine will fire/run when pouring gas down TBI, you can be fairly certain the ignition is good, and the problem most likely is fuel pump. You will need a repair manual for the truck, one that has the electrical diagrams to trace the wiring to the fuel tank, to make sure no wires are broken and you have power to sending unit.

Might check fuel filter, could be clogged up and need replaced.

Just a couple of ideas, hopefully this helps you get the truck running.

Check for spark, if ok spray some carb cleaner down the throttle body while somebody cranks it. If it runs on carb cleaner remove gas cap and listen for fuel pump when key is turned to run, if the pump runs but makes a gurgling noise the 2 inch hose above the pump split
I have a 90 GMC 1/2 ton with 277,ooo miles on it, only let me down twice, once at the mail box that was the split hose above the fuel pump in the tank. It was the original pump at about 260000. A year or so later it would'nt start in the garage, just tapped on the fuel pump relay and drove it to town and got a new relay.

Check for spark, if you have that then its probably fuel pump. You should here the fuel pump run for about 3 seconds and shut off, when you turn key to run position and before turning key to the crank position. if it doesn't run, find the fuel pump relay unplug it, find the wire to fuel pump on relay plug, put direct battery voltage to socket for FP in plug. If fuel pump runs, its probably relays gone bad.If it doesn't run either its the fuel pump or broken power wire to fuel pump. Usually when i do a fuel pump i also replace fuel pump relay. as fuel pumps wear, they draw more amperage to run over time, and it causes contacts in relays to get pitted/arc burns from opening and closing.

Fuel pumps in the tank. and it can be a PITA if all the strap bolts and straps are rusted away, and fuel lines (pressure/return) to pump/sending unit assembly nuts are corroded to crap.

Best to remove the box from the frame. Not that hard to do - even by yourself. I drilled thru the rafters in my garage and installed 1/2 inch bolts that stuck out. They were placed at each corner of the box. I used ratchet-type tie down straps, removed the cargo bed bolts, fuel filler neck and tailight wiring and ratcheted the box high up over the frame. From there you'll have a clear view of the top of the tank and the fuel pump mounting hole in the tank. Replace the fuel pump assembly. Be prepared to replace fuel lines and brake lines in that area, especially if they are severely corroded. Please keep safety in mind!

If it's the original fuel pump, it's long overdue for replacement. If it's been replaced once and the vehicle has over 200K on it, it's probably due for replacement again.

As mentioned, the other likely suspect is the ignition pickup in the distributor. These have very fragile wires that are subject to breaking. You should first verify that it's indeed a fuel problem by spraying a bit of starting fluid or carb cleaner in the throttle body.

My 88 chevy pickup quit starting out of the blue. Turned out to be a temp sensor. Was causing fuel to be dumped into the engine and flooding it out. Good luck- joe-

Best thing about having the fuel pump in the tank is that it pretty much eliminates vapor lock.

I think what you meant is vacuum in the tank caused by a plugged tank vent. That happens too but in my experience the engine will idle okay but you get no get up and go.