88 244 Sedan Repeated Fuel Pump Relay Failure

e777 · Post by **e777** » 17 Feb 2017, 10:51

Hello,

I searched the forum but could not find this information.

I vaguely remember reading somewhere that if one of the two fuel pumps fails, then it produces an overload situation for the fuel pump relay, which will continue to fail after replacement under the excessive load. Or am I imagining this...??

Anyway, my 244 is driveable for a short while before blowing out the relay, which then needs replacement. Once replaced, the car starts and runs fine for some hours.

I should add that leading up to this it had a hot start problem, which I also recall being related to fuel pump failure, in some instances.

Any thoughts on my relay problem?

Thanks!

Eric

93Regina · Post by **93Regina** » 17 Feb 2017, 12:07

e777 wrote:Any thoughts on my relay problem?

Naw, no thoughts about relays, but using a amp meter is your friend...right at fuse holder location.

e777 · Post by **e777** » 21 Feb 2017, 08:20

Thank you. I will let you all know what happens.

e777 · Post by **e777** » 21 Feb 2017, 09:51

IPD has a "Top 10" list of problems of the 240, here: https://www.ipdusa.com/techtips/10081/t ... 240-models

There, you will find this information:

Fuel Injection Relay 1978-1985 240 Models
The main fuel pump relay can be troublesome causing intermittent stalls and hard starting. The most common failure is overheating of the main 12V power connection to the point that the solder joint fails. This is usually caused by a failed pre pump in the gas tank, which in turn causes the main fuel pump to be overworked and draw excessive amperage that overheats the circuit.You can confirm this failure by popping the cover off the relay and inspecting the solder joints on the circuit board.

This also pertains to fuel pump relays on later models:

Fuel System Pre Pump 1978-1993 240 Models
The pre pump is a low-pressure, high-volume pump that sits inside the gas tank and supplies fuel to the main high pressure pump under the car. When it fails, symptoms include poor idle quality, hesitation when accelerating, reduced fuel economy, loud humming noises emanating from the main pump and accelerated wear of the main pump. Faulty pre pumps can also lead to hi amperage loading of the fuel pump electrical circuit resulting in blown fuses and or failed relays as mentioned above.