Possible carb trouble
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Possible carb trouble
Hi gang Took the truck out for a spin around the block today. Was running great and all of a sudden, it felt like it was starving for fuel.. The hood is off so I could see the glass fuel filter and it was full. It died a few times but started right up. I opened the fuel cap just in case, but it was not that, Got it back to the shop and did a look see, but could not determine anything obvious, When I gave it a lot of gas, it would start to die. I'm thinking the float might be sticking.
The carb was professionally built several years ago, but the truck was never on the road,, It has run fine except for today. All fuel lines, tank, filter are new. No junk in the fuel pump bowl or the filter.
How would one go about checking the float for sticking? Any other ideas would be appreciated.
The carb was professionally built several years ago, but the truck was never on the road,, It has run fine except for today. All fuel lines, tank, filter are new. No junk in the fuel pump bowl or the filter.
How would one go about checking the float for sticking? Any other ideas would be appreciated.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
90% of carb problems are electrical.... Sounds suspiciously like a bad condenser or coil. If the float were sticking open, it would reek of gas and wouldn't likely re-start easily. If it were sticking closed, it would slowly fade until dying, then you'd have to crank quite a bit.
Thread Starter
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Thanks Ross. Added symptoms. When I shut truck off last night, I could watch the fuel in the filter drain. That usually takes several weeks to do.
Also, I have a pertronix ignition with new coil, (,the coil could still be bad).
There was no smell of gas around carb. Not sure how to procede
Also, I have a pertronix ignition with new coil, (,the coil could still be bad).
There was no smell of gas around carb. Not sure how to procede
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
What engine and carb do you have? Is the filter you are referring to the glass bowl on the fuel pump? How fresh is your fuel pump?
I assume the Pertronix setup isn't new, that you've been driving with it long enough that there's confidence it is correctly wired etc?
I assume the Pertronix setup isn't new, that you've been driving with it long enough that there's confidence it is correctly wired etc?
Thread Starter
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Hi Ross It is a 279 (Lincoln) holly carb. The truck has been running just fine for a couple of years, although I just put it on the road after several years with the cab off. I have run it over the years in my shop and driveway, The fuel pump was rebuilt. Actually the carb was rebuilt near you. An outfit called Pony Carbs. I think he is no longer there. Total miles put on the truck since I've owned it is about 20. If need be, I can make a video of it while it dies off and send it to you. Raining heavy now, so I'm not in the shop. The gas is fresh and in the new tank and lines. I have been adding fuel stabilizer also.The filter is glass type after the fuel pump and before carb and is clean and full. The bowl in the fuel pump is clean and full. When filter is full, truck starts immediately.
If it is the coil, how will I test it.? Pertronix Flame Thrower 40011
This should be a good challenge.
Thanks for your help. I enjoy learning
If it is the coil, how will I test it.? Pertronix Flame Thrower 40011
This should be a good challenge.
Thanks for your help. I enjoy learning
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
That's a very powerful coil. Did you buy the ignitor unit at the same time? That coil can only be used with specific ignitors, newer ones. See here: http://www.pertronix.com/docs/instru...eets/44011.pdf
You might check to see if the coil is real hot when it dies.
On the chance it is the carb, and it's the float sticking closed, try rapping on the top of the carb near the fuel inlet with the plastic handle of a screwdriver, when it starts faltering.
You might check to see if the coil is real hot when it dies.
On the chance it is the carb, and it's the float sticking closed, try rapping on the top of the carb near the fuel inlet with the plastic handle of a screwdriver, when it starts faltering.
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Yes Ross. I had Pertronics speck out the units and purchased them at the same time from Pertronics.
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Fleet Mechanic
Joined: Jan 2007
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From: Eastern shore,Salisbur,MD
I will try taping on the carb when I get out to the shop. Also, I will check temp of coil
Thanks
Thanks
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Ross,
Been in the shop today. Had truck Idling about 15 min or so. when I gave it gas, sometimes it would idle back down and then quit. I touched the coil and it is to hot to touch. So possibly back to what you were saying a coil going bad?
Now I just went out again to fuss. I relocated the coil. It had been mounted on the intake manifold. Moved it to the fire wall. Took a ohm check when it died. 2.1 ohms. It is a 1.5 ohm coil.
I will check fuel flow after lunch just to make sure I have pressure and will let you know what I am finding.
Been in the shop today. Had truck Idling about 15 min or so. when I gave it gas, sometimes it would idle back down and then quit. I touched the coil and it is to hot to touch. So possibly back to what you were saying a coil going bad?
Now I just went out again to fuss. I relocated the coil. It had been mounted on the intake manifold. Moved it to the fire wall. Took a ohm check when it died. 2.1 ohms. It is a 1.5 ohm coil.
I will check fuel flow after lunch just to make sure I have pressure and will let you know what I am finding.
Thread Starter
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Ross,
The coil was hot at the time. Took pos wire off, read between pos and neg on the coil. Running 12v neg ground. Voltage at voltmeter on dash is about 14V when truck is running..
Just had lunch going out to check fuel pump
The coil was hot at the time. Took pos wire off, read between pos and neg on the coil. Running 12v neg ground. Voltage at voltmeter on dash is about 14V when truck is running..
Just had lunch going out to check fuel pump
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
That coil is available as either 1.5 or 3.0 ohms. It is printed on the coil label what model you have. If it's a 3.0, you may have some shorted windings. Try it when the coil is completely cooled, see if it's different.
Have you run the fuel pump outlet into a can to see if it's really putting anything out? The drainback may indicate the check valves aren't sealing correctly, or a hole in the diaphragm. Any gas smell in the oil?
Have you run the fuel pump outlet into a can to see if it's really putting anything out? The drainback may indicate the check valves aren't sealing correctly, or a hole in the diaphragm. Any gas smell in the oil?
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Good morning Ross,
Trouble shot problem late yesterday afternoon. Separated fuel line after filter to carb. Glass bowl on filter was full, but nothing came out while cranking. Separated fuel line from pump to filter. Lots of gas came out. Put a new filter in this morning and just came back from a test ride. ALL is good. Re-tuned my carb to highest idle when engine is hot. Running like a top. I will still check with pertronics on Monday to see what the temp should be on that coil. It is still hot to touch but not as hot as yesterday.
Thanks for all your assistance. I appreciate your knowledge
JimG
Trouble shot problem late yesterday afternoon. Separated fuel line after filter to carb. Glass bowl on filter was full, but nothing came out while cranking. Separated fuel line from pump to filter. Lots of gas came out. Put a new filter in this morning and just came back from a test ride. ALL is good. Re-tuned my carb to highest idle when engine is hot. Running like a top. I will still check with pertronics on Monday to see what the temp should be on that coil. It is still hot to touch but not as hot as yesterday.
Thanks for all your assistance. I appreciate your knowledge
JimG
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