So, I've been running out of fuel at high power, (over 500hp) and starting to run lean. Not lean enough to be *bad*, but lean enough to make me concerned. So, I start digging. And I keep digging, going through all kinds of trouble, and checking all kinds of things. A fair number of decent possibilities turn up along the way.
The fuel system has a Mk4 Denso pump in tank feeding into an externally mounted Bosch 044 that provides the actual line pressure. Among other things, I decide I don't like that particular setup, and elect to pull both those pumps off, and replace them with a dual in-tank setup consisting of two Aeromotive Stealth pumps. Originally I was going to go with dual Denso pumps in tank, however, after buying an additional pump and dropping the tank, I discovered there is NO WAY that's going to fit without some serious mods to the tank.
Anyway, back on track. While I have the hanger out, I figure I'll check the electrical connections. So I hook the system up, throw it in a bucket of fuel, run the feed line into another bucket, hook it up to 12v and put a meter on it. I'm not seeing 12v at the pump... why is that? I check the wires... they suck. They've been spliced several times, with different wires, etc. That's ok, I was planning on running new wire while I was in here anyway. Replace the wires, check again. Better, but still not good. Some more testing narrows it down to the ground wire on the pump hanger... specifically, where the wire connects to the hanger.
It's connected with a rivet - I didn't take a picture, but there is a similar rivet on the inside of the hanger. The external one didn't look any worse.
So I drill out the rivet, and, lo and behold, I'm greeted with this wonder of wonders:
Seriously? How the hell was the in-tank pump running at all? Was it getting some grounding through the tank straps as well? Maybe, but somehow I suspect I just replaced a whole crapload of expensive parts because about 12 cents in connectors, wire, and rivets was badly corroded.
Moral of the story: Check your wiring before buying new parts. All of it, even if dropping the tank is a serious pain in the ass.
The fuel system has a Mk4 Denso pump in tank feeding into an externally mounted Bosch 044 that provides the actual line pressure. Among other things, I decide I don't like that particular setup, and elect to pull both those pumps off, and replace them with a dual in-tank setup consisting of two Aeromotive Stealth pumps. Originally I was going to go with dual Denso pumps in tank, however, after buying an additional pump and dropping the tank, I discovered there is NO WAY that's going to fit without some serious mods to the tank.
Anyway, back on track. While I have the hanger out, I figure I'll check the electrical connections. So I hook the system up, throw it in a bucket of fuel, run the feed line into another bucket, hook it up to 12v and put a meter on it. I'm not seeing 12v at the pump... why is that? I check the wires... they suck. They've been spliced several times, with different wires, etc. That's ok, I was planning on running new wire while I was in here anyway. Replace the wires, check again. Better, but still not good. Some more testing narrows it down to the ground wire on the pump hanger... specifically, where the wire connects to the hanger.
It's connected with a rivet - I didn't take a picture, but there is a similar rivet on the inside of the hanger. The external one didn't look any worse.
So I drill out the rivet, and, lo and behold, I'm greeted with this wonder of wonders:
Seriously? How the hell was the in-tank pump running at all? Was it getting some grounding through the tank straps as well? Maybe, but somehow I suspect I just replaced a whole crapload of expensive parts because about 12 cents in connectors, wire, and rivets was badly corroded.
Moral of the story: Check your wiring before buying new parts. All of it, even if dropping the tank is a serious pain in the ass.