Bronco 5.0 speed density EFI mystery

[63A]

Injectors is next. I investyigated the ECU because it was fairly simple- always hoping for something easy.

Does the Ford EFI batch fire the injectors or is each one fired independently?

 

[Timmy390]

Injectors is next. I investyigated the ECU because it was fairly simple- always hoping for something easy.

Does the Ford EFI batch fire the injectors or is each one fired independently?

All speed density that I've worked on was batch fire.......that includes the 96 E350 van I converted to MAF

Tim

 

[BanditBronco]

Injectors is next. I investyigated the ECU because it was fairly simple- always hoping for something easy.

Does the Ford EFI batch fire the injectors or is each one fired independently?

I would do some research and double check, there were crown vic's with SEFI speed density set ups.

 

[63A]

I asked because I'm also working on an Opel Kadett that I swapped a GM 3.1 V6 into. The early 90s GM EFI is batch fire (one bank at a time) which caused me some diagnostic issues when I was doing the wiring swap.

 

[Viperwolf1]

Injectors is next. I investyigated the ECU because it was fairly simple- always hoping for something easy.



Does the Ford EFI batch fire the injectors or is each one fired independently?

Only truck and van was batch fire. Cars were sequential whether HO or non-HO.

 

[truecountry]

Check the egr valve if you didn't delete it ...I had one to get stopped up and didn't want to run right and shut off at stop light ...another thing I had happen was the fuel pump wiring at the alternator if you used all the wiring harness it tends to burn in the plug easy to check unplug harness to alternator its a short harness

 

[63A]

More info:

I used a stethoscope to listen to as many injectors as I could reach, all I could get to are firing.

I got another ECM from pick-n-pull. No change to symptoms.

My previous fuel pressure checks with diagnostic gauge were done with my Bronco parked and used dash gauge to monitor while driving. This afternoon, I parked my Bronco at the bottom of my driveway (approx 25 degree upslope) and connected the diagnostic FP gauge. On my last few test runs, I've been barely able to get up the driveway- basically had to let it idle up the driveway. With the external FP gauge attached and the engine loaded trying to go up the driveway, the fuel pressure would start at 34 but would begin to decrease (bleed off) if I applied throttle to get up the driveway. If I continued to applied throttle, the FP would continue to decrease well below 20. If I let off the throttle, the FP would slowly climb back to 35ish.

The fuel pump is an 80s F250 external high pressure EFI pump which should provide plenty of volume for my 302. I also tried a new pump and no difference. I don't have a fuel filter after the pump and I've tried running it without the fuel filter and it did not make a difference. I also pulled the pickup/sender out of the tank and I don't see anything that would be limiting fuel flow/volume.

I have not replaced the fuel pressure regulator so maybe that is worth a try.

 

[Sporto]

You may be onto something with the fuel pump failing. I would test the voltage at the pump to See if you’re getting an intermittent signal, it should be battery voltage at the pump. Could be bad relay or connections or maybe a ground at the ECC. . The FP is powered by a dedicated relay circuit that is grounded through the ECC via pin 22. The ECC’s ground wire should also be checked. It sounds like you’re getting a weak or intermittent power signal to the pump. Do you have a shut off switch on the FP monitor circuit? Pin 19, that’s also a potential weakness in your ability to properly pump fuel. Maybe loose connections around that switch.

Just some thoughts on things to check.

Good luck!

Rich

 

[jagbucket]

how are the fuel lines ? could have a restriction and not able to flow under higher demand.

 

[ransil]

More info:

I used a stethoscope to listen to as many injectors as I could reach, all I could get to are firing.

I got another ECM from pick-n-pull. No change to symptoms.

My previous fuel pressure checks with diagnostic gauge were done with my Bronco parked and used dash gauge to monitor while driving. This afternoon, I parked my Bronco at the bottom of my driveway (approx 25 degree upslope) and connected the diagnostic FP gauge. On my last few test runs, I've been barely able to get up the driveway- basically had to let it idle up the driveway. With the external FP gauge attached and the engine loaded trying to go up the driveway, the fuel pressure would start at 34 but would begin to decrease (bleed off) if I applied throttle to get up the driveway. If I continued to applied throttle, the FP would continue to decrease well below 20. If I let off the throttle, the FP would slowly climb back to 35ish.

The fuel pump is an 80s F250 external high pressure EFI pump which should provide plenty of volume for my 302. I also tried a new pump and no difference. I don't have a fuel filter after the pump and I've tried running it without the fuel filter and it did not make a difference. I also pulled the pickup/sender out of the tank and I don't see anything that would be limiting fuel flow/volume.

I have not replaced the fuel pressure regulator so maybe that is worth a try.

similar issue I had a few times, 2 times it was something in the fuel sender lines, looked like leaves, it did have a strainer on the tank side, failed to remove all of it the first time, third time my spring cut the 5/8" vent hose and trail junk got into the tank, clogged up the LP pump prefilter about a dozen times about every 25 miles.

blow out the lines change filters.

make sure pump is not loosing voltage