I have a 1993 Volvo 240, automatic with 131K original miles, I am the original owner. Last month I noticed when the fuel level got to 1/3 tank the idle was rough and it had poor acceleration. Took it to my mechanic who I have used for years and specializes in VW, Porche, Audi and Volvos. He checked and the pre-pump in the tank was not running, making a buzzing sound. He ordered and replaced the pre-pump with an aftermarket. Idled great,started right up, thought we were done. Drove it locally for 3 days it was fine.

Monday, had to get on the expressway to work, had to get on it harder than I had since I picked it up and it starved for fuel, backed off the gas pedal and it caught. Called him up, he said has to be the pre-pump. he would install a new one. He did , exact same issue.

What should we look at next? Is there a way to check the volume of fuel the pre-pump should push, also what fuel pressure should I see at the fuel rail. Are there better pre-pump than others.

Any help would be greatly appreciated.

Lewis

 

Do we assume he replaced the little rubber fuel line on the bottom of the pump. If it is the little bellows type rubber hose they usually crack and then the pump will suck air when the tank is less then a 1/3 to 1/2 full.

 

on LH2.4 cars like yours, the fuel rail should be 42-44 PSI when the vacuum line to the fuel pressure regulator is disconnected (or with the pumps jumpered but the engine not running).

 

Fuel filter is the first thing I'd look at--under great demand for fuel any restriction will make it act up.

 

my 740T wagon suffered from power loss under heavy acceleration twice.

first time, it was the in-tank pump not working right, when the fuel level was below about 1/3rd, it would suffer under full throttle acceleration and sputter til I backed off on the throttle. I might note, there have been ongoing reports of aftermarket in-tank pumps that were wired backwards, so they sucked rather than pumped... see In the Tank - 240 Volvo Tank Pump and Sender

the second time I had this problem was probably turbo-specific, under heavy boost, the silicone rubber big pipe from the turbo to the intercooler was blowing out from under the clamp at the turbo side. the rubber had turned to mush due to the oil spray from the older turbo. interestingly, it gave almost the same symptoms as the tank pump problem.

 

The fuel filter by the main pump was replaced at the time the pre-pump was done. Also the hoses and sock were replaced when we did the pre-pump.


We just got done pulling the 2nd new pre-pump and it is not running smoothly, we are returning it. Is there a particular make / model pre-pump that is recommended? Part numbers would b great.


Thanks for the help
Lewis

 

https://www.fcpeuro.com/products/vol...-delco-3507436
or
https://www.ipdusa.com/products/5993...-fuel-pre-pump

I would for sure replace the small hose inside the fuel tank AND the pickup 'sock'

after installing the pump, disconnect the hose from the tank into the fuel filter+main pump assembly, stick into a clear container, and power the in-tank fuel pump and verify that a good stream of fuel comes out... I think it should be something like 0.5 ounce per second (that would be enough fuel to go 100MPH at 7MPG, which is kinda max everything flat out).