Won't Start

[Racer-G]

I have a 1987 Chevy Scottsdale C30 short axle dually with a 350 tbi, 400 auto, with duel tanks. recent fuel pumps and in cab switch. New coil, plugs and wires all done with in the last 6 months. New map sensor about a year ago. It has been running great .

I drove 30 miles to the mall, was doing some Christmas shopping, looking for a parking spot when all of a sudden the motor just quit. I rolled into a spot and restarted the truck, no problem. Could not see anything wrong under the hood. Did some shopping came back out, started right up. Drove for 15 minutes quit again saw the engine light. Stopped put it in park, switched the tank started right up. I pulled into a parking space. Seeing the engine light reminded me that I needed to top off the oil, it was a quart low. Got back in and it started right up. Drove down the highway another 5 minutes quit again. Coasted to the off ramp put it in park. But this time it would not start. tried a couple of more times and still nothing. The ECMB2 fuse was blown. Replaced it, started up but was not wanting to accelerate. When I gave it gas it wanted to die and it was running ruff, so I just let it idle while I got under the hood. It was getting gas just running ruff. About a minute later it quit again. Tried to start it, nothing. Yup ECMB2 fuse blown again. Damn no 10 amp fuses left, lets try a 15 amp. Popped it in and started up still running ruff. It didn't take long and I started to smell that smell I just hate the most, burning plastic. So I shut her down immediately and the fuse was blown.

I got her towed to were I was staying.

The next day I got a box of 10 amp fuses. Having been stranded off the highway I never could hear the fuel pumps work. I popped in the 10 amp and it would not start. Both left and right pumps sounded normal like they always do when I start it up. The fuse was not blowing. I poured some gas in the throttle body, hit the key and it started up and ran until it was out. The fuse was not blown. Tested both fuel pump relays with another new one I had with me, so its not them.
I am at my mothers house about 700 miles from home and I don't have an electric tester.

It is at this point where my knowledge is limited and I could sure use some help, ok a lot of help. I'd like to get back home some day.

Thanks in advance for all your help. Hope you all had a great Christmas. I know I did.
Racer-G

[franken]

I can't say it'll help or if its accurate, but take a look at the diagrams in the link.
Look for a wire shorted to the engine, melted or rubbed off insulation. Since its somewhat intermittent, this seems likely. ORN should mean orange, so look for an orange wire... Then try disconnecting nonvital things. Needless to say the ECM and pump are vital. You said you had dual pumps. Does the fuse blow when either pump is in use?

http://www.justanswer.com/car/0zt0r-...fuse-mark.html

[Racer-G]

I did forget to mention that I did check the wires by the firewall. I also looked at a bunch of posts in this and other forums before I posted this. Most were fuel pump or lack of spark related and some posts just ended without giving their results. I did double check the firewall in case I missed something. My wiring at the distributer and oil pressure switch have that plastic shielding and are not that close to the firewall and I don't see any chafing. I pulled out the glove box so I could see the ECM unit. All the wires looked or felt in tact.

I think that because the 1987 model is a little more unique (last year of body style, first year of tbi ect...) it might be more difficult to dignose. Did this year truck have a plug in to do diagnostic checks?

[Dead Parrot]

First thing I thought of is a fuel flow problem. Since it does it with both tanks, check things after the Y connector where fuel from each tank enters a common pipe. Line blockage or plugged filter would be my first choice. Not sure where the pressure regulators are but a plugged line/filter might cause the pumps to work too hard and either overheat or blow a fuse.

A plugged filter is consistent with your symptoms of limited fuel flow, running briefly after being stopped for a bit, and running fine if you manually pour fuel into the intake.

[Racer-G]

Sounds plausible. The fuel filter is an AC Delco that I put in new 8 months ago when I flushed the tanks and put new fuel pumps in. I got a feeling it might not be it, or at least I think the odds are against it. But I am not ruling it out. I would be an easy fix.

[franken]

A clogged filter won't cause excess current and fry the fuse. Only pump relay current goes through the fuse and that's constant.