playing in the snow-in my driveway-idling perfect dies[like someone pulled a power plug] ive been down this road before-sort of-[tbi probs] 90 sub 5.7 so i pull some codes 44,45 --really? so because i had one ,i change out the fuel pump-thinking fuel pressure-no start no power to pump-so i try the relay direct power to pump -nothing-fuel into the tbi ,starts up then when fuel is gone-dies-i swapped out all electrical sensors even threw in a new dizzy pickup and module,nothing- from the back [pump] i follow the wires to the oil pressure sensor could this be shutting down my pump...... PS pump does work if i jumper it straight to battery,but i wont try to run my truck like that, oh and no power to injectors
CK5
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no start !please help?
- Thread starter only 31s
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Have you checked the fuel pump fuse yet?
The oil pressure switch actually doubles as a fail safe for the fuel pump relay in the event it goes bad, as long as there is 5 psi of oil pressure the oil pressure switch will feed power to the fuel pump.
The oil pressure switch actually doubles as a fail safe for the fuel pump relay in the event it goes bad, as long as there is 5 psi of oil pressure the oil pressure switch will feed power to the fuel pump.
4xcrazy
3/4 ton status
same exact problem i am having with my Burb now, i gave up on it for now, it's too cold where it's parked to work on it.
Thinking about this more after reading your post again you have an issue with the wiring somewhere between the fuel pump relay and the pump if you power the test lead at the relay and the pump won't work but you can direct power the pump and it works. You now need to recheck the power wire from the relay back to the pump VERY CAREFULLY.
Check the fuel tank switch on the dash. That was the problem on my 91 crew cab.
My truck would run with carb cleaner sprayed into the throttle body, once I stopped the truck died. I was only getting 8.5 volts at the fuel pump. Tried bypassing relay with the red wire coming off it but nothing happened. Only way I could get the pump to work was running a hot wire straight from the battery. Checked all the lines from the tank to the firewall looking for a short, finally led to the fuel tank selector switch. Jumped the appropriate wires there and she started right up.
My truck would run with carb cleaner sprayed into the throttle body, once I stopped the truck died. I was only getting 8.5 volts at the fuel pump. Tried bypassing relay with the red wire coming off it but nothing happened. Only way I could get the pump to work was running a hot wire straight from the battery. Checked all the lines from the tank to the firewall looking for a short, finally led to the fuel tank selector switch. Jumped the appropriate wires there and she started right up.
I'm pretty sure he's working on a 1990 Burb which means it only has one fuel tank and no selector valve.
thought i had it
so ive been making long jumps in the wires from the pump-got the pump to work through the key -and the pigtail to power it[the pump] manually.[just to see if it was not a relay prob]so that told me the wiring must have had a break in it ,so i fire it up starts for 7 or so seconds and dies-has not started again ,but now even with my jump wire[from pump to firewall]not relay-no start--could a bad oil pressure switch be shutting me down? can it tell the computer to not fire my injectors,and not send power through the circuit to my pump? am i crazy ?
so ive been making long jumps in the wires from the pump-got the pump to work through the key -and the pigtail to power it[the pump] manually.[just to see if it was not a relay prob]so that told me the wiring must have had a break in it ,so i fire it up starts for 7 or so seconds and dies-has not started again ,but now even with my jump wire[from pump to firewall]not relay-no start--could a bad oil pressure switch be shutting me down? can it tell the computer to not fire my injectors,and not send power through the circuit to my pump? am i crazy ?
If you know you've got power to the pump now (at least by running a jumper wire) and the pump is working but the truck won't start you might have a bad hose inside the tank from the sender to the pump (there have been a few post recently with people having issues with that hose being split).
i wish it were that easy
i know the pump and hose are good cause its the first thing i swapped out[trap door in back of the burban makes it easy] something new-i left that jumper wired up for an hour or so--[went in to get warmed]came out and it didnt work anymore-it blew out my ecmB fuse-could where the bad part of the wire have rubbed the frame or a ground and blew the fuse? i guess the only way to rule it out is to cut out the suspected bad wire and see if i happens again just using the jump wire-but its cold and the ground is froze-i wish i had a garage..........and heat..........and and and ,OK -OK im going back out ,Thanks
i know the pump and hose are good cause its the first thing i swapped out[trap door in back of the burban makes it easy] something new-i left that jumper wired up for an hour or so--[went in to get warmed]came out and it didnt work anymore-it blew out my ecmB fuse-could where the bad part of the wire have rubbed the frame or a ground and blew the fuse? i guess the only way to rule it out is to cut out the suspected bad wire and see if i happens again just using the jump wire-but its cold and the ground is froze-i wish i had a garage..........and heat..........and and and ,OK -OK im going back out ,Thanks
update--- fixed
after checking a multitude of wiring -i pretty much gave up [do to the horrible weather] so i started from scratch- so it was bad brand new or it fried out from the bad fuel pump wire---IGNITION MODULE
was the no fire problem-- i know ive seen at least 20 posts that say have them test it 3 times when you buy it -the autoz,and advanced look at me funny-we cant test those-so its always been a gamble-3 of them in 6 years-the other 2 worked fine but #3 became #4 after return
Thanks guys
after checking a multitude of wiring -i pretty much gave up [do to the horrible weather] so i started from scratch- so it was bad brand new or it fried out from the bad fuel pump wire---IGNITION MODULE
was the no fire problem-- i know ive seen at least 20 posts that say have them test it 3 times when you buy it -the autoz,and advanced look at me funny-we cant test those-so its always been a gamble-3 of them in 6 years-the other 2 worked fine but #3 became #4 after returnThanks guys
