Poor Mileage & Whine from FP area

[JimG]

I have a in-tank Walpro with the inline pump deleted. Today I noticed a whine for the fuel pump area and experienced really poor gas mileage ie: around 9mpg. Any thoughts on what to check? Pump, FPR etc.

[jkxr4ti]

I would be looking for a vacuum leak first. That will cause FP to increase at idle and cruise and reduce milage. Check the vacuum tree as well. There should be one cap on there and it can deteriorate and get launched off with some boost if it’s not a good cap or clamped in some way.
Next check the oil and see if it’s level is high or smells like fuel.
Either one of those things can signal a ruptured FPR diaphragm.
You can disconnect the vacuum line at the FPR and pull a vacuum with a hand pump/mighty vac if you have one of those too. If the Regulator can’t hold a vacuum then that’s a good sign the diaphragm is going and the regulator needs to be replaced.
You’ll want to change the oil right away too since you will have excess running into the crankcase.

[my8950]

I have a in-tank Walpro with the inline pump deleted. Today I noticed a whine for the fuel pump area and experienced really poor gas mileage ie: around 9mpg. Any thoughts on what to check? Pump, FPR etc.

Way back I recall reading and hearing people say that the pump was whining before it would fail.
I would say to put a FP gauge on and see what is going on with pressure, that would also help you to determine if possible vacuum leak as mentioned above. You may also want to check the fuel filter, my guess is you put fuel filter inline where the old rail pump was? Also possibly the sock in tank filter is clogged with junk from inside the tank causing the pump to work harder.

[andyofcolumbusmerkur]

I wonder if the noise and the poor mileage are related. I have seen xr4ti sending unit assemblies that had a Walbro installed too low. The in tank filter was touching the bottom of the tank. It still was able pull in fuel but not as well. I like the design of the stock in tank filter better. If something was clogged or failing I would think that you'd notice a lack of power not bad fuel mileage. Could something be wrong with the return line? Maybe look along the bottom of the car and see if something was damaged like from being jacked up. If the car was running really rich all the time you should be able to smell gas at the exhaust tip. It makes me think something else is going on like a leak.

[Ed Lijewski]

I'll just add that if the fuel level is low the pump, OE and/or aftermarket, will be heard clearly in the cabin.

As well, I found the Walbro 260 too noisy, period.

I'd check for a fuel line leak somewhere also.

YMMV

[zxr250cc]

Hi all,

One area of in tank fuel pumps that is not explained usually is that the fuel pump is cooled by the fuel it is immersed in. For longer pump life it is good to keep a 1/4 tank or more to help in pump cooling and to live longer. Running around with an almost empty tank forces the pump to run at higher temps and also is noisier.

Cheers