93 4.0 swap into 87 bronco ll issues

[moosemeadows]

I'm having some issues with my swap with drive ability problems. Main issue is when its warm it doesn't want to start. If I floor the pedal it'll start indicating an issue with the injectors but if I don't touch the pedal it'll start also but only run for 10-15 sec then die acting like fuel starvation. If I feather the pedal it'll run but the idle is 12-1500. Stone cold it starts right up and idles around 8-900 but the idle increases as it warms up. Seems backwards to me low when cold and high when warm. I'm old school and know carbs not fuel injection and with a carb I'd be looking at choke issues. I get no codes from ECM using analog voltmeter not even 11 saying it's ok. Checking my TPS @ grey/white wire KOEO I get 4.9v where it should be less than 1v but moving the throttle thru range it goes to 5v smooth and steady up and down. Also at TPS checking for 12v at ground I only get 7.5v I've replaced ECT for ECM temp sender for dash gauge cleaned MAF and throttle plate ISM checks good and was cleaned changed frame rail and in tank fuel pumps and pressure is where it should be changed fuel filter in tank and frame rail. I'm running out of things to check and I know that someone has been down this trail once before. Not very electrically inclined but follow instructions well so if you have thoughts or further tests send em my way and I'll do my best to get back to ya.

 

[trashtruck]

hook up a fuel pressure tester to see what the fuel is doing but it sounds more like an air intake issue.

 

[moosemeadows]

fuel pressure is 40 with key on and 35 idling with vac hose on FPR

 

[trashtruck]

someone with more electrical knowledge should be along shortly, (I hope) but my book shows the tps to be connected to both temp sensors so it may be an issue with any of that system.

 

[Centaurious]

It sounds like you have a Power or Ground problem at the ECU, verify this first. most of the 3 wire sensors have 12v on one wire, Ground on the third, and the middle wire has a variable voltage from it. Check the TPS for 12v and Ground, if it is wrong the power or ground to the ECU is bad or the ECU has problems

 

[moosemeadows]

I have 4.9 v at the grey/white wire where it should have less than 1v but when I move the throttle thru it's range it goes to 5v smoothly up and down. Now at the ground wire I have only 7.5v where there should be 10-12v. By those results I'd guess the TPS is ok but there's an issue in the wiring right or the ECM is toast.