Hey All,

I've been reading up on this site a bit, and I have a problem with a questionable solution. I bought my car a couple months ago, and noticed the fuel pump is not priming, and doesn't kick on until oil pressure rises. The car starts, and runs fine after that.
Today, after checking all the grounds/wiring (with a lot of help from this site, I might add), I pull the ECM down and test the A1 pin. No signal when ignition switch turned to "on"(not for 2 seconds, not at all). Upon further inspection, I noticed a t-tap on the green/white wire of the FPR had been installed. I think the previous owner hooked up a fan override switch incorrectly, grounding the g/w wire on the FPR instead of the fan relay. I am sure a transistor was fried in the ECM.

Well, I have a fix that works??? I ran a wire to the t-tap on the g/w wire on the FPR, to a momentary N.O. switch (3A, 125V), thru a 10A fusible link, and finally to an IGN terminal on the fuse box. This allows me to push my button and prime the fuel system when I turn on the ignition, and BOOM! she fires up!

My question is, am I going to harm anything? Does the burned transistor in the ECM have any effect on anything other than fuel pump prime? Will my HACK work until I can scrounge up ECM$$$$???

 

Welcome to TGO

A used ECM from JY can be sourced for about $40. Your hack is just that - a band aid, but it should get you by. The fuel pump relay is used to carry current to fuel pump in the gas tank, while oil pressure switch is used as safety back up to the FPR in case it fails. FPR contacts are rated for 30 AMPS and circuit wiring is 12 AWG (orange and tan-white wires at the socket) - the oil pressure switch wiring is 16AWG (just above oil filter).

Pin A1 is used to provide a switched 12 volt supply to FPR - you are correct about transistor.

//RF

 

Thanks for the quick reply and welcome. MAN, THESE BOARDS ARE ADDICTIVE! When the tax man cometh, so does my ECM! By the way, the g/w wire to jump the relay is more like 18-20 gauge, I didn't measure current draw, but I think my 10A link would be fine for hundreds of 2-3 second bursts.

 

Yea, they are...

Green-white wire from Pin A1 is a control element output line - relatively low current. IFRC FPR coil is about 110 Ohms on BOSCH style relay which will draw about (give or take) 110 mAmp of current. 18AWG is adequate for this application. Oil pressure switch on the other hand has to carry FP current. Stock pumps draw about 3 to 5 Amps, performance pumps are higher.

//RF