2.3L ('83-'97) Low Fuel Pressure

[Papas97]

I have a 97 Ranger 2.3 Manual that will crank but not start. Checked with starting fluid and it’s runs for 5 seconds. Checked Fuel Pressure at the rail and it was 22. Cycled key a few times and never went above 22. Jumped relay so pump would run continuously and still 22. Pulled return line off at pump and fuel was being returned at 22 psi. I assumed the Regulator was bad so I replaced it and still got the same results. If I crimp the Return Fuel Line just before the tank I get 45 psi at the rail. Any ideas what would cause this? Fuel Pump was replaced 2 years ago.

 

[Dirtman]

Did you replace it with a motorcraft pump?

 

[Papas97]

I just got the truck from my Dad and he said that it is an aftermarket pump.

 

[Shran]

Clogged up filter and/or strainer in the tank could be a potential issue or just a weak pump. It's hard to find pumps that last more than a couple years.

 

[Dirtman]

Yup unless you get an OEM pump a couple years is a pretty good lifespan...

 

[Papas97]

Update: New Fuel Pump, Filter and FPR. As soon as I turn the key to ON, fuel immediately comes out of Return Line at tank. It acts like the new FPR is bad. At what psi should the FPR open? I can crimp the return line just before the tank and it idles fine. As soon as I remove the crimp it shuts off.

 

[Dirtman]

Is the vacuum line to the regulator broken?

 

[Papas97]

Is the vacuum line to the regulator broken?

It looked fine but I will pressure test it. Wouldn’t the vacuum only come into play when the engine is running? I’m getting fuel through the return line for 2 seconds each time I turn the key on and no psi increase at the rail.

 

[Shran]

You should see fuel returning to the tank... that is normal. Pressure spec for your truck should be something like 30psi at idle and 35-40ish if you crack the throttle open (low vacuum.) The pump is probably capable of 60-70psi and the system is designed to allow excess fuel to return to the tank, otherwise you'd be seeing higher numbers at the rail, and you do on newer trucks that have a returnless system.

What's not normal is the low pressure situation you've got and I'd be checking voltage at the pump at this point.

 

[Papas97]

You should see fuel returning to the tank... that is normal. Pressure spec for your truck should be something like 30psi at idle and 35-40ish if you crack the throttle open (low vacuum.) The pump is probably capable of 60-70psi and the system is designed to allow excess fuel to return to the tank, otherwise you'd be seeing higher numbers at the rail, and you do on newer trucks that have a returnless system.

What's not normal is the low pressure situation you've got and I'd be checking voltage at the pump at this point.

Voltage at the pump is good. Still can’t figure out why it runs fine with return line crimped. One thing that I did find was the hose from the engine to the evap canister is dry rotted and broken. Would that have anything to do with idle? From what I could find online it looks like that hose should connect to the steel line that is sticking through the intake near the FPR. That line has a rubber cap on it.

 

[Shran]

Could cause a vacuum leak but capped off, it shouldn't be a problem. Have you checked for a plugged up tank vent line, the one that runs from the top of the tank to the evap canister? Perhaps you've got some sort of vapor lock going on?

Hate to suggest pulling the fuel rail off and cleaning it out, but maybe it's rusted out internally and partially clogged? There was some mention of that happening in the 2.9 forum recently.

Kinda grasping at straws here.

 

[Papas97]

Could cause a vacuum leak but capped off, it shouldn't be a problem. Have you checked for a plugged up tank vent line, the one that runs from the top of the tank to the evap canister? Perhaps you've got some sort of vapor lock going on?

Hate to suggest pulling the fuel rail off and cleaning it out, but maybe it's rusted out internally and partially clogged? There was some mention of that happening in the 2.9 forum recently.

Kinda grasping at straws here.

I thought about vapor lock and pulled the vent hose off as well as took off the gas cap. Is it normal for a regulator to open at 20psi? Both new ones I’ve tried do the same. When I had the return line crimped it was idling smooth and as soon as I removed the pliers it immediately died.

 

[Papas97]

Update 2:
Replaced PCV and cleaned MAF and IAC and still same issue. Tried removing the plug on the Coolant Temp Sensor to check for corrosion and the sensor broke so I replaced it. Still will not idle when cold but once it warms up it seems ok. I did notice that the a/c compressor clutch was cycling which caused a rough idle. CEL is on and has been for years. Got a Bluetooth OBD2 scanner and it didn’t have any codes. Going to do a compression and vacuum test soon.

 

[Papas97]

Update 3: Did a vacuum test and it was fine. Pulled codes and got a P0102 MAF Circuit. Replaced Air Filter and tested MAF Sensor. Getting 14.3 volts in Red Wire and both grounds measured .2v and the return wire was .83v and did increase with throttle. MAF is testing good. Cleared code and CEL stayed off for about 5 minutes and then returned. Is there anything else that can set off that Code?

 

[cbxer55]

Yup unless you get an OEM pump a couple years is a pretty good lifespan...

We'll see. I had Sears put a pump in mine in November 201, it was cold and I didn't feel like fuckin with it (they were also less than a mile from my home). Still going strong today. It has nearly 20,000 miles more on it now than it did then. I do run Marvel Mystery Oil in the gas at a ratio of about one ounce per gallon. Been doing that in all my vehicles since way back in the early 80's. Ranger is the first vehicle I've ever had to replace the pump in. Checked fuel pressure a couple months ago, still up over 60 psi. I'm happy. Ranger is happy.