Fuel Issues

[the_intimidator03]

Well I have been trying to figure this out for a couple days. its an 88 ford ranger extended cab with 2.9/5speed.

I am not getting any fuel pressure to the rail. I have located what I believe is the fuel pump relay on passenger fender well (black/green skirted relay) behind the starter solenoid. behind it is another relay which I assume is PCM? it is black/brown (not 100% sure)

I went under the truck and didn't feel either pump vibrate when engine turned to run. on the frame rail mounted pump there is a 2 wire round connector that I checked the voltage on and got 6.8 volts with key on. Also when I press the schrader valve on the fuel rail I get no fuel or maybe a little dribble.

I had the truck up and running and drove it around the lot and it ran fine. standard 2.9 tick and me stalling it a time or two due to not driving a manual in a while.

So I am not sure where or what I should do next.

A couple other questions I have are. I believe the fuel filter is AFTER the fuel rail pump with 1 line in/out. I have another canister or such that is before the frame rail fuel pump that I am not sure what it is.

Edit: I found the inertia switch (was a little further to the left and under the carpet) Reset that and still nothing. Ill try a bypass on it this week when I have some time.


Edit: Update 08/6/12 Ok so I have done some electrical testing to try and get some date for yall.
First off the inertia switch...... It is not hooked up. It appears it was bypassed using a 15 amp buss fuse. The 2 wires that are on that (which I must assume is for the inertia switch) is a Orange W/ Light Blue stripe (hot I believe) and Pink W/ Black stripe (to pump). Given this is correct the following voltages are accurate and true to what s happening.
With the key in the run position I check voltage to the fuel pump(hi pressure frame). So I disconnected the 2 wire connector(black wire and Pink W/black stripe) and got 6.6-6.8 volts Reconnected the plug at fuel pump.

Now the following voltages are with the fuse in place and fuel pump hooked up (hi pressure frame) and the key in the run position.
Orange w/Light Blue stripe. 2.4-2.5 V
Pink w/ Black stripe 2.44 V
Same settings with fuse removed.
Orange w/Light Blue Stripe 6.8V
Pink w/ Black Stripe 2.4-6.4 (very erratic readings)

Now These readings are with the key OFF and fuel pump(hi pressure frame) and Fuse in place
Orange w/Light Blue stripe 2.5
Pink w/ Black Stripe 2.5
Same settings with fuse removed.
Orange w/Light Blue stripe 3.1-3.3
Pink w/ Black Stripe 2.2


Those are all the readings I did tonight. I also swapped in my Fuel Relay out of my 86 cougar and there was no change in readings. I don't really have a spare PCM to try out. I need to work on getting a fuel system electrical diagrams. Kind of curious if my EVTM from 87 thunderbird would be close enough

 

[Pony]

have you changed the fuel filter?

 

[the_intimidator03]

Not yet. when I have an afternoon off I will pull the filter. I intend on picking up some more parts this upcoming weekend after another payday. I just ran out of time today to fickle with it. What gets me is the 6.8 volts at the High Pressure pump with key on and no buzz/vibration when key on for either in tank or rail pump

 

[Pony]

All i can say is the fuel pump im new to trucks/cars so sorry man :/ just got my ranger and all i need is fan and fan clutch then i can piece or buy a lift

 

[pcollins]

If you bypass the inertia switch and it does NOT fix your problem, just make sure you put it back the way it was. If you bypass it and it does fix the issue, replace it properly

 

[freedom5]

The green base is the fuel pump relay. The brown base is the PCM and if there is one with a black base it is the A/C compressor cut out which cuts power to the compressor clutch when accelerating rapidly.

freedom 5

 

[the_intimidator03]

ok thanks freedom... I do not have A/C in my truck. Ill do a bypass and some testing this afternoon on the fuel electrical system. Much appreciated... will update with report tonight

 

[the_intimidator03]

BUMP!!!.. Just updated it with testing from tonight. Hope yall can help point me in the right direction. Right now I feel it is more electrical than mechanical( pumps/fuel filter etc)

Back to work on it again this afternoon. will post any more findings

Also noticed another thread that if i leave the key on for 3-5 seconds voltage should drop from 12 volts at the pump. and that around 6.8 volts remain after the 3-5 seconds is normal if not a little high?

 

[the_intimidator03]

Ok. Ive done some more extensive testing. I retested my intertia switch bypass.. 11.70 volts initially then drops to 6.7-6.8
I tested PCM and Fuel Pressure Relay and results are as follows:

the way i numbered these pins are with the securing latch on the right side... top left being 1 (empty pin slot) and top right pin is #2 then bottom left being 3 thru 5 left to right. (hope this isnt too confusing)
Both PCM and FP relays unplugged (just testing the plug wires) Key OFF

FP relay PCM
1. no wire 1. no wire
2. 12.00V 2. 12.00V
3. 0.00V 3. 0.00V
4. 4.2V 4. 0.00V
5. 0.5V 5. 4.2V

PCM and FP relays both plugged in.. Key On Engine Off
FP PCM
1. No Wire 1.No Wire
2. 12.00V 2. 12.00V
3. 4.2V 3. 0.0V
4. 4.2V 4. 0.0V
5. 0.5V 5. 4.2V

PCM and FP Relays tested with Key On Engine Off
FP
1. No Wire
2. 11.67V
3. 11.67V
4. 11.67V
5. 11.67V(when key turned on) dropped to 1.19V
I noticed some voltage changes on pins 3-4-5 when the dome light came on when i opened the door to turn the key.

PCM
1. No Wire
2. 11.67V
3. 0.4V (drops back to 0.00V)
4. 11.4V
5. 11.67V
pin 4 and 5 had some voltage changes with the dome light coming on.

Are these numbers correct?

So after I did those test I decided to pull the fuel lines starting at the fuel filter... turned key on and no fuel came squirting out.. so I reconnected it.. I also did this for the high pressure pump and what ever the canister is between the tank and high pressure pump. same results. Afterwards I decided to spray some ether in the intake and fire it up... it decided to rev to the moon ( shut it off before it hit 5,000rpms) and restarted it with same results. shut it down again. 3rd time i decided to give it a minute then attempt to start it again... it fired up and ran... idled. so i drove it around my lot and pulled it back up to the shop and noticed some new wet spots. so I checked under the truck and found fuel leaking from the top of the tank. It was spraying out around the sending unit.
the only thing I have done with the sending unit is feel the hoses and connections and now i have a leak.

My thoughts is when I removed the fuel lines the release of pressure may have unlodged something?

Really sorry for the long winded kind of jumbled post. I cook under the sun all day on the farm and im dog tired