Ok i have a 86 f250 with 351w holley 4180 and c6 tranny. I got it for $125 owner said it needed a rear main seal. We dropped tranny changed seal, changed tranny fluid, tranny filter, resealed tranny pan. Then found out it had wrong carb so i got a holley that would work, rebuilt carb. Also plugged all vac ports except pcv and distributor advance. Replace intake manifold gasket. Checked fuel pressure good at 5psi, checked compression around 120psi, oil pressure at idle around 20psi, checked vac at good at 20in at idle also checked timing at 10btdc. Once thing i did noticed is that it was hard to set timing its was like to light didn't always flash. (Maybe i'm used to 4cylinder engines) Or should the timing light be flashing like crazy. Because i'm getting like a flash pause maybe flash pause flash. instead of what i'm used to is flash, flash, flash. So when i try to start it I have to pump gas pedal to start and when fast idle cam checks in it will idle sometimes. Sometimes it will stall when put in gear others times not. Its weird. Sometimes it will idle perfect other times not. This weekend i drove it down the street and before coming to a stop it stalled. And its hard to restart. ITs like urg, urg, like hard to turn over. Then it will finally spin and catch. I checked voltage at ign module and it looks good 12volts. Although i checked voltage at coil and i'm getting 12-14volts. should it be around 6volts. Do i have a bad ballast resistor or bad ignition component. Or what else should i do. Thanks

 

Does your carb have the fuel level site plugs on the sides of the bowels? If so, I would check the fuel level and see if it's right. It should be just a little bit below the hole.

 

ill check it maybe tomm. I know for a while i didn't have any fuel in the primary bowl and i adjusted it although the truck was parked somewhat on a downhill slope. Plus i needed gas. So ill get it level and check the sight plug and let u know.

 

Also i checked all the electrical connections. I checked to make sure i had power after all fusible links. I even wiggled the electrical harness and wires with engine running and no change. One thing i did notice was that the distributor was loose when i got it. the put that the vac line hooks too that screws unto the side of the distributor was loose so i tighten those up. Although i have noticed the the top half and the bottom half of the distributor has play in it. I can turn the top half around plus or minus an inch or so. Is that normal?????????

 

Your vacuum advance might be pulling your advance out of phase.



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Ignition Lesson of the Month: Hystereses, the difference between the timing as the rpm and vacuum increases to the timing as rpm and vacuum decrease, needs to be kept to a minimum. A precise advance curve accomplishes this.

 

If it has tension on it and springs back when you let go, that's normal. That's the advance mechanism working. Which reminds me, did you set the timing with the vacuum line unhooked from the dist? You should have.

 

you know what i checked the sight plug and fuel level is ok. I went to start truck. I pressed the gas pedal like 3 times and turn the key and the truck started and ran. It idled ok. I pulled each spark plug wire off the spark plug and no change that i noticed. I even adjusted the mixture screws and no change. Then i put my hand over the choke plate and the idle raised. I put it in gear and the truck idled in gear. It ran like rrrrrr hick up rrrrrrrr hick up rrrrrrr hickup hickup. Like it was missing or something. So i had my neighbor sit in the truck in drive while holding the brake. While i went through each spark plug wire again and no change, adjusted idle mixture screws and no change. Then i put my hand over the choke plate and the hickup went away it idled perfectly. Is my choke adjusted wrong. OR do i have a vac leak somewhere? Right now the way the choke works is that it is near closed when i start it then after running it will eventually open slightly then fully open where the choke plate is at the 12oclock and 6 oclock postiion. Is that to far opened??? Do i need to adjust back?

 

oh yeah i also turned the distributor when it was running and no change i'll check for the spring action tomm. I really wasnt looking for it. Although i truck will run i can get the gas and it will go. I just need it to idle right and not stall.

 

from what i've read that's normal. The choke is slightly open when cold and then fully opened when running at normal operating temp.

 

sounds loke your choke is ok, when you are putting your hand over the carb to smooth it out you are richening the mixture, so its lean for some reason. Could be a vaccum leak or misadjusted carb (probably vac leak)

 

where else could i have a vac leak??? i've gone through all vac lines. Replaced carb gaskets and intake manifold gaskets. Do u think the carb could be leaking? Well i noticed the choke needed some adjusting according to another thread because it would not open and close freely. So now it does that. How far does the choke plate open??

 

The choke opens straight up and down when the engine is warm. If you are richening the mixture by holding your hand over the carb, turning the idle mixture adjustment screws out should help a little, though you might be just covering up a vacuum leak like someone else suggested.

One other thing. See what the secondaries look like. Loosen the screw on the secondary shaft and see if they seat better. If the secondaries are not closed most of the way, they will let too much air by and make it run lean. They should be open just a little bit where you can barely see a crack.

 

There should be a tube going from the air horn, down to the exhust manifold, and back up to choke assembly.if there is a hole or those tube are broken you will have a vacuume leak.or if those tubes have Been removed make sure where the tube enters the choke assembly is plugged off or there will be a vacuume leak as well

 

you know what it was running ok and then i would not stay running. Then i could not get it started. So i started checking things out again. Funny thing. I have no gas in the primary carb bowl again. Weird. There is either something wrong with the fuel system or someone is siphoning out my gas. I just went from a half of a tank to nothing with maybe just three start and 40mins of running. There is no way the truck is using that much gas. Next question is when i open the gas tank cap there is no pressure on it like i have noticed on my other vehicles. Is this normal on a carbureted vehicle. This is the first one that I have owned. I know the fuel pump works I had a guage on it before and it was putting out 5psi. Although the book says that i need to check for volume. Then again i remember when i had the carb float adjusted too high and gas started shooting out of the carbon canister. So i don't know if i punctured the canister there or if there is a clogged fuel line. Or something else. What should i check for? How common are these gas tank to rust? I think i'm goin to replace all the rubber fuel lines soon anyway to eliminate that possibilties. Plus i may drop the tank to see what it looks like. Now i think the problem is fuel related and it being starved of it somewhere.

 

oh yeah where the tube enter the choke assembly. Does anyone have a pic of it?