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| Shakedown test failed, fuel issue? (Page 1/1) |
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California Kid
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JUN 27, 12:25 AM
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Hey everyone,
So the shakedown drive (more than a 2 mile circle) unfortunately did not go well and I ended up having the car towed home. For reference Dave Tarcy and I did an oil change, emptied the gas tank and refilled with new gas, and replaced the MSD ignition box and distributor cap. Motor ran well during testing and I did short drives Saturday and Sunday (2-3 miles) without issue. Tonight here's what happened.
2 miles from home: Motor struggled hard leaving a stop light. Very low rpms and rough running with my foot to the floor, felt like it was going to stall. After 2 seconds, everything sprang to life and I took off. Ran fine.
6 miles from home: Motor dies on the road at 50 MPH. Shift out of gear and car restarts after 3 cranks, shift back into second and proceed to my in-laws house.
8 miles from home: Arrive at in-laws house. Brother-in-law wants a ride so I take him for a two mile loop. No issues at all. I get back and my nephew shows up and he wants a ride. I don't make it 400 yards before the motor dies. After 3 cranks it fires up and we get another 100 yards before it dies again, can't start it again. Need to have it towed.
So Dave thinks there's a fuel delivery issue that we need to sort out. Based on the highly intermittent nature of the problem, does anyone have some suggestions? Fuel pump relay? Pump itself? Any recommendations on how we might troubleshoot the issue would be most welcome.
Thanks,
D
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Habanera Hal
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JUN 27, 12:58 PM
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Sounds silly, I know, but sometimes it's the simplest things. Have you checked the fuel filter?
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damittron
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JUN 27, 02:11 PM
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And...does it have an Ignition Control Module? I don't know the bigger engine you have in this, but if it has one, replace it. 
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Fiero38SC
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JUN 27, 02:25 PM
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Fuel filter is the fist thing I thought of too. Also assuming that the temperature is good and oil pressure is good.
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California Kid
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JUN 27, 03:04 PM
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Oil pressure and temps both look normal so we should be good there. We had the fuel filter out prior to emptying the gas tank and it looked good. Although we haven't inspected it since we got the motor running.
I just replaced the old (according to Dad) faulty MSD box with a new (purchased 6 years ago but never installed) MSD 6AL Digital. I would hope that the new one isn't faulty from the get go, but read the internet for more than 10 minutes and you'll find a thread complaining about failed MSD ignitions. This is the third one this car has seen since 2002 alone. Is there a basic test I can do to determine the health of the new MSD box?
Not to ask a dumb question, but I'm trying to learn how to take care of this. If the fuel filter was clogged enough to stall out the motor; why then would I be able to restart the car (at least earlier in the drive) and have it pull strong when I did some mild showboating for my brother in law in between issues? Can someone explain how a filter issue would cause this?
D
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edfiero
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JUN 27, 03:13 PM
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you need to get a fuel pressure gauge on there, and see what you've got when the car is having a problem rather than guessing that its a fuel issue.
Typically if you have a fuel restriction it's going to idle OK but fall on its face when you start pressing on the pedal / get it under load.
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Gall757
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JUN 27, 03:20 PM
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MSD ignitions are designed for racing. Most people buy one or 2 items in the ignition system and leave the other parts stock. They run at over 3 times the stock voltage, so any weak link....(dist. cap or spark plug wire).....will tend to fail.
The fuel filter may be just barely working, so fuel pressure stays up until higher demand catches up to it and pressure drops. cheap to replace, and a good idea.
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Spoon
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JUN 27, 03:43 PM
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I'm also in the fuel filter corner. I had similar trouble with a non-fiero years ago (74 Lincoln) and It would just stop running. Crank on it and no luck. Wait 10 minutes or so and it fired right up and would be good for a few days. Finally it would not restart anymore. Discovered no gas to carb. Long story short it was a clogged fuel filter.
Filter was no bigger than a grown mans thumb in length & diameter and it screwed right into the Carb. Often wondered who in their right mind at Ford would come up with an idea like that for an engine with 460 cubic inch (7.5 Liters) getting 8-10 mpg on a good day. Nevertheless it seemed that once a year this filter would clog up so don't overlook the sometimes not so obvious.
Spoon------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
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viperine
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JUN 27, 10:08 PM
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I am not very familiar with the car yet, I've noticed a post or two, but I am guessing a small block Chevy? Fuel injected or carb? A fuel filter could be the issue as mentioned. You could also be suffering from heat soak or vapor lock. It depends on the fueling setup.
Ensure adequate clearance between the exhaust and fuel lines and other fuel components. Insulate anything that can't be re-routed. A carburetor can suffer as well, if equipped. I have resolved this issue with a carb spacer (my choice was phenolic ((plastic)). A Fiero may not have clearance if you have a carb.
Proper fuel pressure is important as well, since fieros came with electric in-tank pumps and that SBC's used Mechanical pumps for carbureted models and likely electric pumps with different output values from the v6 that fieros we're best equipped with.
Just some stuff to check.
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Fiero38SC
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JUN 28, 09:47 AM
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