DezmoDog My last post was about ECU issues. The latest saga is a fuel pump issue. I put a new ECU and chip in my 851. It's a 1992 ECU (P7) in a '91 851 using a new Ferracci chip for a '91. I turned the key today and the fuel pump won't run. I tried the new chip in the new ECU, the old chip in the new ECU, and the old chip in the old ECU, none of them worked. They were all installed correctly. Fuses are all good, when the key is turned on the relays click. I pulled the connector at the fuel pump lead and when they key is turned there is a little over 12v at the lead for a couple seconds then nothing, no problem there. Jumping power directly to the pump results in the pump running. Maybe not as strongly as I'd expect, or maybe I'm imagining that part, but in any case it's running. Hook up the connector, nothing. The relays still click of course but no pump. Ok, so that sounds like a bad connector but honestly I can't see how that can be. It's not a complicated part and everything seems to be fitting how it should. So my question is, could a fuel pump go bad sitting over the winter, to where it's finicky regarding the voltage needed to make it run? I haven't checked the voltage on the other side of the connector when it's hooked up, I suppose that's the next step. I swear it is one thing after another with this bike. Absolutely NOTHING goes as expected with it.
griff851 Time to have a look in the tank. It would seem there is open circuit between the plug and the pump. Perhaps just continuity tests. Don't want sparks in the tank.😁
DezmoDog I should have been more clear. When I put power into the pump end of the connector the fuel pump runs so I think the wiring is still good. My 996 did the same thing a few years back, a new fuel pump fixed it. Considering the connector is seeing the power it should when it should, I guess I should bite the bullet and order a pump. I think I'll start a pool to bet on which sensor has gone bad which will prevent the bike from starting once the fuel pump is worked out.
erthmvr888 I had a similar problem with my 91 with a S4 955 motor in it. The S4 wire harness and ECU wiring was a bit of a mess - all tie wrapped up by the battery box - so I tidied it up but forgot to ground the ECU. No fuel pump or starter. Looked at it for a month be for I figured it out - grounded the ECU and it all work fine. Trav
DezmoDog So... the battery was on a Battery Tender for days before I tried it out yesterday, but not when I was workign on the bike. When I finished I put it back on the Battery Tender. I was downstairs a couple minutes ago for an unrelated reason. Just for yucks I flipped the key. The fuel pump fired up just like it's supposed to. Now I'm wondering if it's the battery that's toast, I never checked it with a load on it. More troubleshooting to follow, but not today.
pgw I had the exact problem. Relays click, 12v at socket into tank, pump doesn't start. Jump battery to socket into tank and pump starts. Replacing relays fixed the problem. My guess is that over time the relays build up corrosion on the contacts and don't send enough amperage to get the pump started.
