Truck died. Need efi troubleshooting help.

[hammer]

Hey guys,

The story - Went to the local pick n pull. Spent 4 hrs pulling parts only to get to the cashier and realize i left my wallet at home. Its 4 pm. They close at 5. I'm 25 mins each way. Challenge accepted. I bomb home, bomb back, I'm really givn'r. Couple miles from getting back to the pick n pull truck suddenly loses power (im in 5th gear probably doing 80 mph), starts popping out the exhaust. I pull over. Bronco is idling fine. Nothing noticeably catastrophic. I hop back in. Rev it up. Starts sputtering and popping at higher rpm. So I continue on, riding the shoulder, low rpm in 3rd gear. Get back to the puck n pull at 5, turn the bronco off, pay for my stuff and get back in the truck. Wont start.

Ended up troubleshooting for an hour and a half before getting it towed home.

Ford efi. rjm harness. I have spark. I have fuel. I can't test fuel pressure or run codes until sunday. I run a lp pump/accumulator/hp pump. I have fuel to the fuel rail and both pumps seem to be working fine. I have spark but swapped another spare tfi that I have just to try. Didn't do anything, still have spark. Checked vacuum lines. Everything looks fine.

 

[jim3326]

Timing chain, dist. gear?

 

[broncoman805]

Maybe low fuel pressure, clogged fuel filters or bad gas.

 

[broncoman805]

Maybe clogged fuel filters, dirty injectors or bad fuel.

 

[surfer-b]

sounds like low FP, you have enough to run at idle but not high RPM

 

[Broncos n' VWs]

It sounds like low fuel pressure to me.

 

[NYLES]

You and that avatar....um what was the problem again?

 

[Rustytruck]

do the ohms check on the pick-up inside the distributor.

 

[Skiddy]

sounds like low FP, you have enough to run at idle but not high RPM

that would be my guess as well and has happened to me, also if the pump is on a relay it could be bad. I think I have went through 3 think they are getting moisture in them. bypassed for now anyway. guess you will find out when you get the gauge on in

 

[chuzie]

My hard mounted fuel pressure gauge (on the hood) was the single best investment I ever made for my efi system. Instant troubleshooting every time.

Just like the guys above, sounds like a pressure issue.

 

[hammer]

Fuel pressure is good. 40 psi

 

[chuzie]

Pull the codes. You have a leaky injector or bad fpr but that isn't the issue.

 

[hammer]

Comp test was good as well. 150 across the board with one at 148 and another at 170.

Cant find my obd1 scanner. Need to get my hands on that and a timing light.

 

[chuzie]

Jumper the plug and count cel flashes

 

[DirtDonk]

What about the LP pump not keeping the volume up for the HP pump to pull reliably from?
Is your return line plumbed into the reservoir, or the fuel tank itself?

Did a SPOUT connector come undone maybe?
What about a semi-fried TFI module. I know you said you had spark, but what if the thing shorted inside and it's sending a signal to the cold-temp-retard function that's not letting your timing advance? Maybe a quick timing light check will tell you if anything is amiss there.

Good luck.

Paul

 

[EricLar80]

If you have a bronze gear on your distributor, then I bet you it is eaten up.

Eric

 

[hammer]

Got 40 psi at the fuel rail. Got spark to all holes. Got 150+ compression on all holes. Distributor gear is good, pin is still in the gear. Cleaned all contacts in distributor cap. Checked all fuses. Replaced fuel filter. Put it to 10 degrees btdc and stabbed the distributor back in. Switched tfi modules with a spare. Tried spraying gas into the throttle body.

I'm able to get a timing light and code reader on it tomorrow

 

[EricLar80]

Code reader will help a lot. Could be MAF sensor - mine did something similar at one point, but I had fried it by connecting it without disconnecting the battery first.

 

[ransil]

disconnect the MAF it should start without it plugged in, might not run good but should start.

 

[hammer]

Got it running. Coil wasn't producing a strong enough spark anymore. Picked up a spark strength tester. Read that our efi systems should produce a spark strong enough to travel 1/2". Mine was barely able to travel 1/4". New coil and it fired right up. Lesson learned. Having spark is not good enough.