boomboomthump

I was looking to replace my DME/fuel pump relay with the solid state version from F9T. Noticed they have two versions available (standard and pump-prime).

As the name implies, the latter runs the fuel pump for a few seconds at the “on” position (or presumably a split second earlier as you rapidly turn the key). It advertises smoother starts as a result.

Curious on consensus from those that have purchased the solid state DME relay?

mike cap

I bought their standard solid state relay. Didn't see the value of the pump prime version. Car has fired up right away for 18 years. Just my opinion.

tstafford

Same here. Starting has never been an issue with mine either.

BobbyT

I have the "pump prime" one, and like it very much. It is a good fuel pump test occasionally to turn the key to on, and hear the fuel pump power up before starting.

AOW162435

Same here.



Andreas

SpeedyC2

+2 on the "pump prime" version.

boomboomthump

Thanks guys. I was thinking the same thing... "is this fixing a problem that doesn't exist?" but then inline with some others figured it may come in handy to have that feature. It's only an extra $8.

Just wanted to see if anyone had any reasons why this would be a bad idea (can't think of one).

pp000830

Am I missing something, I have the original relay and sometimes I hear the pump run for a moment when I turn the ignition on but have not turned it to the start position. Is this what is being referred to as a priming function above? I would think the running of the pump relates to some sort of pressure sensor on the high side of the pump.
Andy

911PERVY

Pump prime relay is not required on a 993

Meenrod

I believe the 993 already have 'pump-prime' built into their ECU/DME so it is not required for us. That option is for 964 cars.

I think that is what I recall when I last looked into this.

boomboomthump

Haven’t noticed, will give it a try on next start.

Seems they need to update their product page with that info.


thanks!

BobbyT

Hi Andy,

With the stock DME relay, the fuel pump isn't powered up until the engine is cranked over by the starter a certain number of times (30?). I never heard the pump run with the stock relay--other noise obscures it.

The "pump prime" feature on this version of the F9T relay powers up the fuel pump when the key is turned to the "on" position, before the engine is cranked over, for about three seconds, and then turns it back off. This is a way to check periodically that all is good, hear the fuel pump run, and then hear it stop (a safety function--the pump should not run unless the engine is also running).

None of this is required on the 993, it's just a little extra for those of us in the Belt and Suspenders Club...

Ralph3.

I purchased a non priming relay in 2017 shortly after buying my 964 Cab. I felt it improved starting over the stock relay. Always wondered about the priming feature and recently bought priming version and installed. I can hear the pump run for a couple of seconds as soon as I turn the key, haven't noticed any major difference between either version in starting or driveablity since installing the priming relay. No complainants about either one.

Spokayman

Yesterday I switched out the F9 pump-prime relay from my ‘95 968 to my ‘95 Carrera, and I can confirm that it does indeed run the pump for several seconds when the ignition key is switched to the “on” position.
The pump does not run (on either car) with a standard relay, but does run on both cars with the pump-prime relay.

like others I bought the solid state relay a couple years ago because it seemed likely to be the most trouble free option, and I figured the pump-prime function was an interesting feature and a potential benefit for quicker starting.

Meenrod

I just checked on my '96 OBD2 993- fuel pump primes for a few seconds with ignition in on position. Standard relay.

Very strange.