Starting Issues 2.9l 4x4 1986 Ranger (auto)

[paulschmitz82]

Hi everyone,

i'm from germany and in january i bought a 1986 ranger (which is an import car), unfortunately it broke down couple weeks after i bought it, the reason was a broken crankshaft.
So i took it to a U.S Car workshop in germany (which are btw extremly rare) and the guy told me he will do an rebuild of the engine.
But after the rebuild the engine still doesn't want to start, and the guy closed the workshop, so i got back the car which is not running right now.
I actually figured out how to start the engine there are two possible options to do this.
1. you unscrew the valve on the fuel rail which is for presurre measuering, the engine immedieatly starts on the first crank if you do this
2. you open the throttle almost to the max and keep cranking for 30 seconds
otherwise the engine is not starting and the thing is it is running rich and i measured the injection times and while cranking the injection times are extremly high, if the engine is running the timing is perfect.
I also think the reason why it doesn't want to start is because it is running that rich and it's just too much fuel, but i also checked the pressure of the fuel pumps everything seems totally fine, the fuel pressure regulator also works fine.
Maybe anyone could give me a hint, which reasons there are that the engine could run rich?

 

[Jazzer]

Were the injectors replaced? If so, check if they’re the right size/output.

-Jazzer

 

[paulschmitz82]

Yes the injectors were replaced. If the engine is running the output is fine but, while starting it there is too much output

 

[RonD]

Welcome to the forum

On the 2.9l engine there will be a Fuel Pressure Regulator(FPR), used from 1986 thru 1997 on Rangers
Follow the TWO fuel hoses that come in from the drivers side in the engine bay
One goes directly to the Fuel Rail, this is the IN from the pump and filter

The other goes to the FPR, looks like a small can, this is the OUT, unused fuel flows back to gas tank
FPR also has a Vacuum hose attached, pull it off and check it for gasoline, shouldn't be any of course, if you find gasoline replace FPR

FPR sets pressure at the injectors at 30-40psi, so computer know how much fuel will flow out each time an injectors is opened

Leaking FPR would Flood the engine, via that vacuum hose

The fuel pumps are capable of 80+ PSI
So failed FPR, stuck closed, would allow 80+ PSI and way too much fuel would flow out of each injector

To test for stuck closed FPR remove its Fuel Hose, called Return Hose
Put a cup or towel down under FPRs unhooked port
Cycle the key on and off 5 or 6 times
Each time key is turned on the fuel pumps run for 2 seconds, that adds 10psi to current pressure
So even if pressure was 0 psi to start, by the 5th key on(50psi) gasoline should come out of the FPRs open port

Also, if possible, Blow into the Return Fuel hose, its just an open hose back to the bottom of the gas tank, so should be able to blow into it and hear air bubbling up in the tank
If this hose was Blocked..................then same as FPR being stuck closed

 

[paulschmitz82]

thanks for your answer,
i already checked everything you said also replaced the fpr and blew into the return fuel hose.
It has to be a problem with the injection times while cranking, because they are way too high but i‘m not sure what exactly is causing this

 

[RonD]

1986 2.9l will be running Batch Fire fuel injection
On a V6 this means 3 injectors will open for each 1 rotation of crank, on next rotation the other 3 will open
Usually odd and even, i.e. 1, 3, 5 open, then 2, 4, 6 open next rotation

So not Sequential fuel injection, injector opening every 2 rotations of crank(1 rotation of cam)
Although if testing 1 injector's pulse for Batch Fire it would still be 1 pulse for every 2 crank rotations

Have you tested fuel pressure at that port?
As said 30-40psi is spec, no higher than 43psi(FPR rating)


Also you can pull out the computer and have a look at the barrel type capacitors on the circuit board, 2 or 3 of them
These often fail after 20+ years, and leak, easy to replace
They cause fuel pump issues and running issue when they start to fail

 

[paulschmitz82]

yes i have, it was around 35psi so seems fine to me.

 

[paulschmitz82]

i will check the capacitors next days, is there a crankshaft position sensor?

 

[RonD]

No, you have a distributor with TFI spark module, that tells the computer the engine timing for injectors

Crank Sensors(and cam sensors) are only found on distributorless engines

 

[paulschmitz82]

okay good to know. Btw the distributor has been replaced aswell

 

[paulschmitz82]

So i again did some research and measurements, so what i figuered out is that all injectors inject at the same time while cranking. And it should be alternately right? so at first 1,2 and 4 and then 3,5 and six? Does someone know how to fix that? And what could cause that problem?

 

[RonD]

Its called Batch Fire injection and is normal for 1986 thru 1994 Rangers
And its ODD and EVEN, 1/3/5 open, then 2/4/6 on the next rotation of crank

If you look at the injectors wire colors you will see a Red wire at each, 12v wire daisy chained from one injector to the next, and then a Ground wire from computer to OPEN each injector
On Batch Fire there are just two colors for Grounds, so just 2 wires back to computer, each Ground wire is connected to 3 injectors on a V6


Sequential injection wasn't standard until 1995 and the new EEC-V computer, but it was done on some engines prior to 1995, mostly the Ford V8s
Sequential injection requires seperate Ground wire for each injector back to the computer, so different wire color for each injector

 

[rusty ol ranger]

Once its running does it run fine? So its just hard to start?

Have you pulled codes?

 

[paulschmitz82]

Okay thank you good to know

 

[paulschmitz82]

@rusty ol ranger so basically it used to run totally perfect but it started only with the valve on the pressure rail open so fuel could run out. The error code said the ECT was broken so replaced it, now it starts everytime but only 3 or 4 cylinders are running and it keeps broking down