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87 TBI no fuel...

496truck

496truck

1/2 ton status
Joined
Jul 22, 2009
Posts
4,471
Reaction score
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Location
Carver MA
Intermittant crank, no start condition. When it would do this I was also not hearing the fuel pump kick on. I thought it was the relay so I swapped it out with a new one. Also removed and cleaned the ground wire from the tank to frame rail just in case. I have checked the wires all the way down the frame rail and everything looks good. It still has the same problem, but it is intermittant so it's been hard to track down.

I replaced the fuel pump back in September 09 so it's fairly new but could be bad, I guess, and hopefully under a warranty. It was an Airtex unit if anyone has input on that.

Here's the strange part. At one point while it was idling I unplugged the fp relay and it just kept running. Figuring it was residual pressure right? I left it idling for ten minutes with the relay unplugged. I even revved it up a few times thinking it would bog down and stall out but no problems, just kept running. Eventually I plugged it back in and turned it off via the key.

I haven't bought a book for this truck yet so I don't have wiring diagrams but the few places I have checked for voltage seem to be good. Anyone know where the fp relay gets the signal voltage from? ECM or ign switch or straight from the fuse block?

Any insight into this would be appreciated.
 
Airtex is good. I have one. I dont think you unplugged the right relay, it should have died after a few seconds. I think the power comes from the fuse block.
 
It's the only relay on the firewall, basically above the pass side valve cover. I don't know of any other relays in this truck.
 
As long as the oil pressure back-up switch is working you should be able to remove the fuel pump relay and the truck will still run. This is a fail safe back-up system in the event the FP relay does goes bad. Also the truck will still start with the relay removed BUT it will take a few seconds longer before starting since the pressure switch needs to see 5psi of oil pressure to allow the fuel pump to kick on.
 
I guess that switch is workin good. I would've thought there was a fuel cut off if oil pressure was lost. One of the many reasons I like this site: Come up with some oddball scenario and someone here has done it or knows about it.

After doing some more electrical testing I've narrowed it down to the fuel pump. I got it from Advance Auto Parts and they said they would warranty it. So, I guess it's getting another Airtex pump for now.
 
I'll take the free one for now. When that one fails I'll go get a Delco pump but right now it's not in the cards...
 
I work at an advance auto. they should give you credit for the defective airtex one. BUT try to get the Bosch at least. Definitely worth paying the price difference. All the parts houses I've worked at that have carried airtex, a good 50% come back defective with in the first year.

EDIT: its only a $5 difference.. TOPS and a much better quality part. I won't sell an airtex if I can help it.
 
Didn't know that was an option. Thanx for the info!

You wouldn't happen to have a part number for that Bosch pump?
 
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87 k5 new to me

I also have an 87 k5 that I bought and the wire loom leading to engine components off the firewall were missing. I replaced with a 87 1/2 ton truck and with an 87 suburban both comming from a wrecking yard and having the 350 tbi and all the same options but the pins leading into the firewall going to fusebox are different. To make it short I cannot get power to fuel pump!! I can run a hot to the pump and have it push plenty of fuel to the throttle body but wont spray through injectors. I can put gas into the throttle body and it will start and run for a short time but thats all I get. Does anyone know exactly what wire loom I should be looking for or maybe what other problem it fcould be. Oh, Ive checked every fuse and relay.. Help I want to drive my blazer bad just stuck at this point
 
It sounds like your injectors are not firing. Find out why they are not firing, ECM fuse, no power, bad ignition module, bad ECM, check to make sure the engine is properly grounded....

TBI doesn't take alot of pressure, but those injectors need to click open/closed to deliver the fuel.
 
I guess I am one of the lucky ones with an airtex. It is kinda loud, but when I turn the motor on, I cant hear it at all.... lol Its an external though.
 
Won't be able to deal with it till this weekend. Finishing up a floor replacement in a YJ for a guy at work. Once that is done and out the door I'll push the Blazer back in.
 
87 fuel

496truck said:
It sounds like your injectors are not firing. Find out why they are not firing, ECM fuse, no power, bad ignition module, bad ECM, check to make sure the engine is properly grounded....

TBI doesn't take alot of pressure, but those injectors need to click open/closed to deliver the fuel.
Click to expand...

Did a bit more research and was told to look for a fuse link going to the fuel pump relay and to check and see if it id getting power at all times to the a terminal. Now I am really lost. There is no fuse link comming from starter to the relay it just say fuselink on the wire and i am not getting power.
 
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