Low fuel pressure on start/ intermittent starting

I've been fighting intermittent starting problems on my 1998 3.0L Ranger. Note that this is the **RETURNLESS** system, where the regulator is in the tank. The truck cranks fine but sometimes won't start, sometimes starts but idles poorly, and sometimes starts normally. After troubleshooting, I discovered the problem is related to low fuel pressure.


Here are a few examples I witnessed while monitoring the fuel pressure at the fuel rail schrader:

1. Truck starts normally at 62 psi but the idle then drops as the fuel pressure gradually drops to ~40 psi and then the idle suddenly returns to normal as the fuel pressure jumps back to 65 psi.

2. Truck starts normally at 60 psi, but then the idle gets much worse until the truck is barely running as the pressure gradually goes to ~20 psi but again suddenly jumps to 65 psi.

3. Pressure stays at a constant 51 psi but truck won't start despite numerous attempts. One of attempts to crank the vehicle eventually gets the pressure to return to the 60s and the truck starts right up.

4. The truck often has good pressure and starts normally.


Key items to note:

A. Fuel pressure or stalling has never been a problem once the truck is running. The pump runs completely reliably once stable after startup.

B. I have jumpered around the inertia switch and completely removed it from the circuit with no change in behavior.

C. I swapped the fuel pump relay and the adjacent wiper relay in the fuse block with no change in behavior.

D. I have been able to hear the pump running (through the fuel filler neck) during a poor idle event.


I suspect all this leads me to the replacement of the entire pump assembly but want to be as close to 100% certain as possible before I spend a couple hundred bucks on my truck.

The one last item I think could possibly cause the problem is the pressure regulator. However, I CANNOT locate a replacement. Because Ford went to the returnless system in mid-98, every regulator I find is the fuel rail mounted one for the return based system. But my truck was built in June and does not have a return line to the tank.

If anyone has experienced this problem PLEASE come forward with your findings. I am very close to just buying the entire pump assembly.

 

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I experienced the same problem with my '99 4.0, I changed the filter with no improvement. I wasn't sure whether it was pump or regulator, so I replaced the pump- regulator-guage- sender assembly.
The easiest way is to lift the bed off.

 

So replacing the entire pump assembly solved your problem? I'm thinking that's really all that's left for me to do since I cannot locate just the regulator. I'll be ordering soon unless someone chimes in with a better idea. Rock Auto is almost $100 cheaper than stores which brings it down to a reasonable price.

+1 on lifting the bed. I have a 5 ton block and some chain I've rigged up in the bed and I left the bed liner out while I troubleshoot this. I can remove the bed by myself in about 20 minutes. I haven't even tried dropping the tank but I can imagine what a PITA it is removing connectors you can't see.

Thanks for the info.

 

Yes, it solved the problem. I test ran the truck before reinstalling the bed just to be sure. One word of caution, make sure the gas guage is reading correctly as well, my guage varies from 1/2 to 3/4 tank regardless of actual fuel level, something is keeping the float from making full travel......make sure it will have full travel upon installation. My truck is not my daily driver, so I'm just setting the trip odometer and refilling the tank every 100 miles. When the weather's right and I'm feeling motivated I will remove the bed again and correct it.

 

Thanks again Mike.

The fact that your pump exhibited the same behavior helped me pull the trigger on a new pump. It will be here Thursday and I should have it installed before the weekend. I'll post up the results for others to reference.

 

What I have experienced with these pumps is the rubber hose that is down in the tank on the pump assembly starts to deteriorate and starts out with a small hole that eventually grows thus pumping the fuel right back to the tank and low pressures to the fuel rail. Had it happen 4 times on the 98 I had but not on any of the other four rangers I have owned.

 

I would have suspected the same but note that my problem is strictly on startup; never had an issue once the truck is running. If there were a leak in the rubber line then I'm pretty sure it would effect fuel pressure all the time. But that's good info for others who are having fuel problems. Thanks Freaky.

 

Fixt!

I received my new pump last Thursday and haven't had a starting issue since! (fingers crossed) The Airtex pump I ordered from Rock Auto was MUCH cheaper than the local parts stores but note that it does not come with the tank pressure sensor. I ordered it anyway since tank pressure has no effect on fuel circuit operation and since I had no evaporative emissions codes.

Here are a few pics from the swap:

I rigged up some chains in the bed and used a block to lift it. The following has to be removed to get the pump off:
- bedliner
- (6) T55 bolts holding the bed
- (3) 8mm hex heads holding the fuel filler neck
- (2) electrical plugs at rear of bed for taillights and trailer
- (4) beers


Next remove the pump itself. The following has to be removed to get the bed off:
- 3/8" fuel fitting which required fuel line removal tool (use WD-40 on stubborn disconnects)
- hand operated clip for tank venting line (new clip came with pump)
- (1) electrical plug for pump & pressure sensor
- pump holding ring; used hammer and large flathead screwdriver to tap off ring


pressure sensor was removed while pump was still mounted to tank; (channel locks or crescent wrench help to turn the sensor while pressing down with hand)


Old and new


Insert float into tank first then snake the rest of the pump assembly into the opening. Reassemble everything in the reverse order.

 

I ran in to the same issues with my 1993 Ranger.


Symptoms:
-Exremely rough idle for first 30 seconds of startup (sometimes barely turning over).
-No start at all
-No issues with starting.

Once running it would be fine but once I stop, say at Lowes or something, and I try to restart it would not start or have rough start.

I replaced the IAC, cleaned the throttle body and replaced the fuel filter and all tune up parts with no luck.

I never thought to look at the fuel pump because I always heard the whine but the other day I had a no start issue and I removed the cap on the fuel rail and pushed the valve down with a screw driver and found the rail to have very little pressure.

Anyhow, I picked up the ENTIRE fuel pump assembly for extended cab from Pep Boys for $75 (bought online and received 20% off) then replaced the pump and now have no issues. While I had the bed off I noticed that the fuel filler neck was dry rotted (hence why it would spill a little fuel when topping off at the gas station) so I bought a new fuel filler neck from Amazon for $50 (vice $300 at Ford and vice $180 at Pep Boys/Autozone).

Now I have a great running truck again! Probably would have kept dealing with the hard starting and not found hte great tip of just pulling off the bed if I hadn't found this thread.

 

2001 Ford Ranger

Symptom.

1. Engine is hard to start. Intermitedly so it is hard to start but not all the time and mostly when the ranger sets for a long time. New starter so I know it isn't the starter.
2. The engine once started. Runs rough. the only way to keep it running is to push the accelarator and keep the engine running.
3. All of the above but instead of trying to keep the engine idle, I unscrew the gas cap and tighten it back up.
This will either clear up all symptoms or will like tonight keep idling hard.

I am going to take it to the local parts store to see if they can pick up anything on the coder but I wanted to get your opinon on where to start the diognostic.

Thank you

 

TXJames, thanks for the step by step. Need to do this in the spring. This is extremely useful