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Ron, RV Mechanic
Category: RV
Satisfied Customers: 35601
Experience:  32 years Master Tech ASE certified.
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1991 ford holiday rambler motor coach 460 ,port fuel

Customer Question

1991 ford holiday rambler motor coach 460 ,port fuel injection , fuel, good ,new fuel pump, new plugs install got sooty after trying to start pulled injectors 14.4 resistance all the same , all plugs look same . if we disable fuel pump will start with
staring fluid momentarily when fuel rail at pressure 40psi will not start will not fire at all ck spark good and strong , injectors power good noid test all 8 injectors good pulled out hair , cked timing chain turning crank to see if loose seems good , advanced
and retarded dist timing no change have had in put from some of the best fors mech I know??
Submitted: 2 years ago.
Category: RV
Expert:  Ron replied 2 years ago.
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
One common cause on the 1991 for an over fueling concern that is ofter overlooked can be caused by a leaking fuel pressure regulator. Pull the vacuum line off of the regulator and see if there is any signs of fuel in the poet and or the vacuum line, if any is found then the regulator is leaking. Check this and post back and we can work from there.
Customer: replied 2 years ago.
its good no leaks
Expert:  Ron replied 2 years ago.
Okay so when it runs are you blowing black smoke and are the any fault codes setting in the computer?
Customer: replied 2 years ago.
no it wont start, cranks good , fire good timing good ,
Expert:  Ron replied 2 years ago.
Okay so you have checked injector pulse, fuel pressure and the timing, have you ran a compression test on all cylinders?
Customer: replied 2 years ago.
fuel press good tried to run with remote fuel (known good) to eliminate bad fuel has new fuel pump ( ford) oem upgraded
compression 130 140 155 145 155 170 140 145
new plugs in stalled after trying to re start all plugs sooty not wet , if we disable fuel ump will try to run on start fluid , will not even atemp to start with fuel rail pressure at 39 lbs
Customer: replied 2 years ago.
injector noid test all good trigger pulse , power on plus side consistant
Expert:  Ron replied 2 years ago.
The problem dose not like like a fuel pressure concern but more like a fuel control concern. Was the computer ever scanned to see if there are any fault codes setting? The engine does not need to be running to pull fault codes.
Customer: replied 2 years ago.
obd1 no codes
Customer: replied 2 years ago.
sorry code 12 no other codes
Expert:  Ron replied 2 years ago.
Yes I am aware its OBDI, my first impression is you have a bad computer, If you have good fuel pressure, injector pulse , proper timing as well as good compression it should run. The computer controls injector pulse width. Fault codes on the 1991 should be 3 digits, not two.
Expert:  Ron replied 2 years ago.
One other thing that comes to mind with fowled spark plugs is you may have restricted catalytic converters, has the exhaust back pressure ever been checked. It was a common problem in 1991.
Customer: replied 2 years ago.
yes I t has been ck not restriction
Customer: replied 2 years ago.
yes 12 was the code
Expert:  Ron replied 2 years ago.
And how was the exhaust checked?
Customer: replied 2 years ago.
has new converter I will ask tec
Expert:  Ron replied 2 years ago.
The best way to check it is to loosen the exhaust pipes up at both manifolds till you have a healthy leak of air while cranking and then see if it will now start. With everything you have done already there not much left beside either the exhaust or the computer.
Customer: replied 2 years ago.
ok we seem to have flow when we use starting fluid no pump press . we will try you tip it will take some time to do it
I will get back to you
Expert:  Ron replied 2 years ago.
Im here every day, let me know how it works out and we can work from there.
Customer: replied 2 years ago.
Expert:  Ron replied 2 years ago.
Your very welcome, thank you as well.