2.3L ('83-'97) Power to fuel pump

[neinnein_nein]

Just converted to EFI (Lima 2.0 to 88 turbo coupe 2.3) and I don’t have power to the fuel pump while cranking, which I think is the reason it doesn’t start.


it’s a walbro inline 255lph mounted on the frame, it builds pressure, doesn’t leak, and it gets 12v to prime when I turn the key in run, but drops to 0 after that, and no voltage while key is in start. Relay seems fine, fuse is good, intertia switch is bypassed..

one thing I see on the thunderbird wiring diagram near the pump that I don’t have in my truck and or on the Ron Francis harness is a canister purge solenoid. Don’t know why that would matter. I don’t understand what gives the pump power specifically at the moment the starter is cranking.. that seems to be the most obvious problem right now.
I’m also not using the EGR connector, it’s just unplugged..
Could it be that ultimately, the ecu is tripping? I’m not sure how to check that either.

please help me get out of my friends driveway—I want my life and my truck back!

 

[RonD]

Yes, what it is doing is correct, there should be fuel pump 12volts for just 2 seconds with key on, then no volts(well maybe 6v no amps) until engine RPMs are higher than 400, then 12volts will come on full time
Its a safety thing in case fuel line should break in an accident, engine would stall and electric pump wouldn't feed a fire

You can cycle key on and off as much as needed to build up pressure to start engine, if your system is not holding pressure then thats another issue

Try starting engine by manually adding fuel to intake, once its above 400rpm fuel pump should come on, and any air in the system should be cleared out

Computer pin 22 GROUNDS the FP Relay to activate it, Computer is what determines 400rpm from spark module signal

 

[neinnein_nein]

Yes, what it is doing is correct, there should be fuel pump 12volts for just 2 seconds with key on, then no volts(well maybe 6v no amps) until engine RPMs are higher than 400, then 12volts will come on full time
Its a safety thing in case fuel line should break in an accident, engine would stall and electric pump wouldn't feed a fire

You can cycle key on and off as much as needed to build up pressure to start engine, if your system is not holding pressure then thats another issue

Try starting engine by manually adding fuel to intake, once its above 400rpm fuel pump should come on, and any air in the system should be cleared out

Computer pin 22 GROUNDS the FP Relay to activate it, Computer is what determines 400rpm from spark module signal

ha interesting! gonna measure the fuel pressure to be sure it’s keeping it. When I cycle on and off it does sound like it’s building pressure because I hear the pump getting whinier and whinier, struggling to push more gas through the pressurized line.

im not sure where to manually put fuel though. In a carb yes, but this is a closed line up until the fuel rail and the injectors. Will try to find more info. In any case thanks for confirming voltage is normal!

 

[RonD]

PCV Valve hose or Power brake booster hose, any Vacuum port works to get fuel into engine, those are just the larger ones

If its turbo'ed then they may be capped off but there should still be some accessible port in the intake

 

[neinnein_nein]

It’s good to be reminded of that actually because actually, I’m not sure where vacuum comes from with this new engine, and maybe I capped off too much. My 2.0 had a vacuum motor on the cold air intake if I remember correctly. In this case, not sure..


new theory based on your observations. Me not having this and instead having a huge vacuum leak in the intake where the tube from egr valve to header normally is (I’m using a header that doesn’t have an egr port) is messing up the vacuum and fuel delivery:

I’m thinking: weld a pipe from egr valve hole to hole tapped into header. Hook up this vacuum solenoid (harness has a connector for it) and hook up vacuum ports to boost valve and egr valve/intake. I probably just have zero vacuum right now!

 

[MikeG]

Get a fuel pressure gage, don't guess.......

Otherwise you will NEVER have any idea what is happening.

 

[bilbo]

If I remember right the egr valve does not open at idle if it’s working properly. Either way it’s not good to have the tube to the manifold broken or disconnected as it will draw air instead of exhaust and go lean.

I think the vacuum motor you’re referring to might be the actuator for the preheat flapper. There’s a damper that allows the intake hose to draw air over the outside of the exhaust manifold when the air is cold. there’s a thermostat in the air cleaner housing that allows manifold vacuum to open the valve when air temp is cold, then cuts off vacuum and allows the damper to shut when air is warm. If I remember correctly it was called a vacuum motor on the emissions diagram.

Long story short, your engine will still produce vacuum without that device. I agree you’ll want a fuel pressure gauge and probably a vacuum gauge too.

 

[neinnein_nein]

Get a fuel pressure gage, don't guess.......

Otherwise you will NEVER have any idea what is happening.

yep ordered one yesterday, it goes up from an AN fitting in the braided line. i wonder if it's possible to install one on the shrader valve on the fuel rail, that would be ideal.
and also, duh, I was so excited to finally have reassembled the whole engine i never even checked for spark. spark plugs are new and gapped properly but the distributor was kinda old, so checking that first thing.

If I remember right the egr valve does not open at idle if it’s working properly. Either way it’s not good to have the tube to the manifold broken or disconnected as it will draw air instead of exhaust and go lean.

I think the vacuum motor you’re referring to might be the actuator for the preheat flapper. There’s a damper that allows the intake hose to draw air over the outside of the exhaust manifold when the air is cold. there’s a thermostat in the air cleaner housing that allows manifold vacuum to open the valve when air temp is cold, then cuts off vacuum and allows the damper to shut when air is warm. If I remember correctly it was called a vacuum motor on the emissions diagram.

Long story short, your engine will still produce vacuum without that device. I agree you’ll want a fuel pressure gauge and probably a vacuum gauge too.

yeah the egr fully open is not good for sure. and vacuum gauge is a good idea. actually i think i can hook up the vacuum pump i use to bleed clutch/brakes and it will give me a reading. question is how much vacuum i should be looking for but that's gotta be on the boards somewhere. when I started the swap I was weary of adding gauges and wanted to keep everything stock-ish looking and now i'm at the point where I want to toss the entire dash bezel and make a custom wood one with space for a 2 din radio and every possible gauge to monitor everything..

 

[Locotomb]

I just sold a 92 ranger I tricked into running again. It took me awhile unfortunately, but the issue I was having was just like yours. Well, except it’s not a freaking turbo. ( I want to put turbo on my low low. So bad.) nonetheless it ended up being the purge canister causing all of the same symptoms you have. The vacuum hose comes from the bottom of the throttle body, almost right before or after the butterfly valve. Make sure that’s either capped or plumbed in. Not sure for a turbo but. Hope that helps.