Bulk connection at firewall question

b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

Ok everything but the 2 vss wires or hooked up......

Check engine light works, fuses good, fuel pump turns on and I get pressure in the fuel rail, it has spark, spark plugs look wet.......

It cranks but will not fire......And when I turn ignition off the fuel pump runs for a bit before stopping.....also I have the stock s10 fuel pump and sending unit in it but I do have the 255lb pump and Hotwire kit, just haven't installed it yet.
 
Last edited:
Don W.

Don W.

Stab it and steer it
Re: Bulk connection at firewall question

b-rad420247 said:
.And when I turn ignition off the fuel pump runs for a bit before stopping.....
Click to expand...

This part is normal because the fuel pump is also driven by a switch in the oil pressure sender so the pump keeps running until oil pressure drops to -0-. This takes a moment when your oil is cold.
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

I just need to hook up the 2 vss wires, just don't know where to hook them up in the c100....also would not having them hooked up cause my crank but no start condition?
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

Well I might have figured out the crank but no start issue.....hooked up a fuel pressure gauge and took out the bleeder valve on the fuel rail and the gauge reads 0.....I know the gauge works as I borrowed it off my grand national.......I hear the fuel pump come on ....it's a regular s10 fuel pump for a 4.3.
 
Don W.

Don W.

Stab it and steer it
Re: Bulk connection at firewall question

Fuel filter? Bad FPR allowing fuel to bypass? Doubt the second because it's held closed by a spring but anything's possible I guess. You can close the return line with vice-grips to check. Have you changed the pump? Could be a plugged sock on the bottom or if you removed the "pulsater" that hose could have gone bad.
 
DaveP

DaveP

Active member
Re: Bulk connection at firewall question

Connect the fuel pump test wire directly to +12V, the pump should run. The test connector is a single connector on a grey wire, comes out with the wires for the relays over the distributor and the power-post.

Because your S10 is a 91, it was a TBI 4.3. That fuel pump is intended to run at 9-12psi. The SyTy (and L35 CPI engine that begins in 92) uses a different pump (and sending unit) which runs at appx 42psi at idle.
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

I have a 255lb pump from racetronics, just haven't installed it yet, was going to do that Tm.
 
Don W.

Don W.

Stab it and steer it
Re: Bulk connection at firewall question

IMHO you should at least see the 9-12 psi from the original pump. Take the line loose at the rail and see if anything even come out.
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

When I took the fuel pressure gauge off the bleeder and turned key on to prime the pump and it skirts out the bleeder ( took the bleeder screw out)
 
Don W.

Don W.

Stab it and steer it
Re: Bulk connection at firewall question

Duh. I should of thought of that. That just means the pump is pumping something. The question now is at what pressure.
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

Well after hooking up a gauge my fuel pressure goes up to 42lb then drops off when pump stops...I don't see any leaks and i installed a brand new 255lb from racetroix
 
Don W.

Don W.

Stab it and steer it
Re: Bulk connection at firewall question

As you probably know it should hold. Per the manual with fuel pressure not holding start with the pump running (use the jumper) and pinch the fuel pressure line. With line pinched stop the pump and pressure should hold. If yes than the prob is a leak or faulty pump. If no then start over pinching the return line. If pressure holds it's the FPR if it doesn't one or more injs are bad.

Exactly where you are supposed to pinch the pressure line isn't mentioned. You can access the return next to the dist. although pinching it might be difficult.

HTH
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

Ok so did what you said and it indicates a injector or more is bad.......so I took off the intake plenum so I could see down the ports, jumped the fuel pump and I didn't see one injector leak at all...

Also tried different fpr from my grand national.......when I hooked up my Hotwire kit the pump doesn't come on.....cause this is an s10 with a syclone engine.....the pink/black wire for ecm power I hooked up to the left side of fuse ecm1 .....is that a ok spot or where would you hook it up
 
Last edited:
Don W.

Don W.

Stab it and steer it
Re: Bulk connection at firewall question

Well I don't what to tell you next. Although I've never actually done this test I always thought it was a poor test. As in how do you know if you truly have a line pinched off? If your fuel pressure drops to 0 as soon as you shut the pump off then it's going somewhere.
 
b-rad420247

b-rad420247

Member
Re: Bulk connection at firewall question

My bad... paint on back of head where grounds are.....sanded it down, hooked it up and it starte......forgot about it when I painted the engine....but then ran into a bad oil pressure switch giving me max oil pressure, took the one off my s10 4.3 ( had to use a different union) what a pain to get at, but fixed that, now I just need to finish the exhaust
 
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