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Car Dies – Diagnosis Appreciated
In my last three outings of any distance my car has died on me. The most recent instances occurred Saturday night. We were making a 50 minute drive. We had been cruising on a highway for about 40 minutes when we reached our exit. As I was on the exit ramp the car quit running. I was able to coast to a parking lot where I let the car sit for 5 to 10 minutes, and then it started up again and we were able to travel the last 3 miles to our destination. I checked under the hood and the only thing I could see that might be a problem was that the braided fuel line was tucked under the heater hoses and touching the intake manifold. The fuel line was very hot. I thought perhaps it was a vapor lock problem so before we left for home, I lifted the fuel line above the heater hoses, closed the heater hose valve and put some exhaust wrap on the fuel line temporarily to keep it from getting so hot.
However, on the trip home, the same thing happened. After a 40 minute cruise on the highway, as I was exiting, the car died again on the ramp! We were able to once again coast to a parking lot, sit for 5 minutes, then started it up and made it the rest of the way home. I had a similar instance a couple of months ago where as I approached an intersection, it died. Since then I have replaced the coil, alternator, battery, voltage regulator and fuel filter. While driving the car seems to run fine. Water and oil temps are good, oil pressure is fine and ammeter shows a charge. I have a 428 FE, with a Holley 750 with vacuum secondaries and MSD 6AL ignition. I have a little over 18,000 miles on the car and never had these problems until recently. The only other changes I can remember making within the last few months was adding a ½ inch phenolic spacer under the carb, a lower drop base and a taller K&N air filter. Any thoughts on what might be happening? I suspect that the fact that the car died both times on exit ramps after running at highway speeds for 40 minutes is not coincidental. Thanks, |
..electric or mechanical fuel pump?
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It sure sounds like a fuel/heat realted issue to me. When you are cruising along, the fuel is moving through the lines quick enough so it doesn't have a chance to heat up or boil. I would try and isolate the fuel line from any possible heat source.
The only other possibility I can think of is some debris in the carb bowl that once you decellerate or lift off the gas it blocks the fuel from leaving the carb. |
CoERA,
I think Computworks is onto something. I have had the same thing happen to me and it was the Holley electrical fuel pump. There is a long history with these pumps from Holley. I would change the pump if you have electrical Holley and switch to a carter or walbro. The walbro is so quiet that you have to bend over at the rear wheel area just to hear it. Bill |
Ron - It is a mechanical fuel pump.
Bob - I was thinking it was a heat/fuel ine problem too, but I'm not sure why it would crop up after 18,000 miles. I did partially wrap the line for the trip home, but it still died. I only did the part of the line the runs above the intake manifold, but not the part the runs down in front of the engine. I'll try to do a better, more complete insultation job. Also, I'll check the float bowl for debris. Thanks, |
I had a similar problem a couple of years ago, turned out to be the fuel pump was cutting out.
The way to find it was to put a fuel pressure Gage in line and read it in the car as I drove. I saw the pressure suddenly dropped to less than 2 PSI and the car died. A quick way to check for a fuel problem is a can of starting fluid. If it dies and you can get it to run off the starting fuel, then you have a gas delivery problem. Hope this helps. :D |
One other possibility not mentioned and though it is unlikely it did happen to me and one other person here. Our cars were doing the same thing and it was just as if you shut the fuel off. Coast over to the side of the road, wait a while and it would start right up. After two months of trying everything I had it up on a friends lift and we had it running and just happened to be looking at the rubber fuel line. All of a sudden it just sucked closed and the car died. We took the line off and it looked and it looked and felt great but I got a new one and replaced it and never had that problem again. Same for the other guy after I told him what I found. And the part of my line that collapsed wasn't in the hottest location either.
Ron |
It could be an ignition module (not knowing which distributor your using) or a MSD box intermittent failure. You could have a resistor/diode/etc that's heating up and cutting out. As it cools the system starts working.
Carry a known-to-be-good spare spark plug and pull a wire when she dies to see if you've spark. Another thing... as soon as she dies, pull her over to the side of the road, pull a spark plug to see if it's wet.. wet plug = no spark and a dry plug = no fuel.. Dave |
Guys, thanks for the replies.
I've received a few other suggestions and have a little more information. One additional clue is that I experienced sudden, dead silence. No popping, missing or surging before the car died. I also spoke with MSD, since I have an MSD distributor, coil and the 6AL box. They told me that the Blaster Coil 2 should not be mounted sideways. I have mine mounted sideways on the front left corner of the intake manifold. My coil is brand new (since the first stall) and my old coil was mounted the same way. Do you think sideways mounting could be the problem. Also, it was suggested that it could be a bad magnetic pickup in the distributor. I'll try to check that tonight. |
you could have some stray electrical current flowing thru the braided wire covering on your fuel line----this would made a little fuel line toaster and could cause vapor lock---poor grounds( fiberglass cars and boats) cause some wierd electrical things to happen
Jerry |
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Ron61, that's a great tip
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http://www.clubcobra.com/photopost/d.../fuel_line.jpg |
The other thing when it dies is to check the float boals and see if it there is gas in the bowls. If the fuel line collapsed and it died because of no fuel, you will not have any gas in the bowls. If there is gas in the bowls, then you know it is an ignition issue- then try partick's suggestion to check it.
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The MSD box is bad. All pro race cars carry two MSD boxes. Guess why?
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Is your fuel tank vented?
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I've run into a similar problem several times. Thought it was the fuel pump cutting out, but it wasn't the fuel pump.
I think your coil is failing. Here's why: If you run for about 40 minutes, your engine gets nice and toasty. So does the coil. As the coil heats up, the windings on the inside heat up and expand, and when it expands (and presumably the material in the coil is breaking down) it shorts out. When the car cools down, the coil cools and the wires no longer short. Ta-da! It starts up and you drive home. Grab your trusty multimeter and head out for a drive. Don't worry, it will start again, but go somewhere you can get off the road easily. Oh, before you go, test the +/- sides of the coil with your multimeter (DMM). Make sure you have it on Vdc NOT Ohms (common mistake). Head out your for your drive. When it dies, pull over, pop the hood with the ignitiion switch "on" and test the +/- poles on your coils. I'd be willing to bet you'll find that +/- now read the same. I've figured this out on a '70 Camaro, a Fiat Spider, and a Volvo (my wife's car, which spent several days at a Volvo shop with multiple mechanics scratching their balls..., uh, I mean, heads. If this works you owe me a beer and/or a shot of Patron tequila. |
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I'd bet module in the distributor or coil. |
Install 'vent whistles'......
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Thanks for the ideas. In response:
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High Vibration Coil
You are running the High Vibration Blaster Coil PN 8222 and not one of their oil filled units right? The literature suggests that the MSD oil filled coils should not be mounted sideways (thus my previous post was not entirely correct :mad:). Evidently in the oil filled units there is a small air bubble at the top of the coil. That air bubble can move over the windings and expose them. That causes them to short internally.
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