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hi I'm new to this forum, but I have a 93 aerostar 4.0 with a fuel problem. It's running rough and blowing black smoke. Changed the plugs, and still the same problem. I took it to a mechanic and he's baffled by the fact that it won't stay running long enough to run a diagnostic test , but it runs (rough) if he pulls the fuse on the oil pump ?? not sure why it would still run. thats the extent of whats been done and am at a dead end. Any suggestions would be appreciated. Thanks.
I took it to a mechanic and he's baffled by the fact that it won't stay running long enough to run a diagnostic test , but it runs (rough) if he pulls the fuse on the oil pump ??
Oil pump fuse? I have never heard of one before. The oil pump on Aerostars are mechanically driven.
If he pulls the fuse on the fuel pump, the engine would quit after it runs out of gas. Are you there when he pulled the fuse? If so, can you describe where it was? I have a feeling he didn't pull the fuse, but just the plug that disengages the computer. That is a grey plug on a harness on top of the firewall, near the brake master cylinder.
From what you described, I'd say there are four most likely possibilities:
1) Your IAC valve
2) Your fuel pressure regulator
3) Your injectors are stuck open
4) If you are unlucky enough, Rbastado had pretty much the same symptoms and it was his engine computer that quit. That would really be a bummer!
By the way, I just had to ask. Are you sure the plug wires are on correctly? Sometimes, when people change plug and wires, they cross a couple of them and wham, car runs terribly or not at all with lots of black smoke and an occasional backfire. I have done that a couple of times.
Thats a possability that the wires were crossed but it was running the same before the tune up. I wasn't there when he pulled the (fuse) he just called and told me.He said with the fuel pump off it would stay running just rough. he sounds kinda clueless. I guess thats kinda scary seeing he's ASE certified specializing in fuel problems. however I appreciate your help. I'll metion these things to him and well- we'll see. Just tyring to get home to Georgia. Thanks
.....you're right Tonto, he suffers from excess gas.......but ole' copper is hot on the trail. Let's leave the horses here and sneak up behind those rocks and watch what happens.......