642 starting problem

[drdent]

My 642 with ford 4 cyl has had a starting problem for a year or so. the engine is old and worn out so I removed the engine and had it rebuilt. everything in it is new and the bolt on parts (carb, oil pump,ect.) are also new. I have it back together and it runs great. It still has the hard to start problem that needs addressed now. It seems to take 5min of cranking to get it to run. once it starts it will restart with no problems for a while. but if it stops for a couple hours or overnight it will take 5 min to start agian. it seem that it is not holding fuel pressure, like maybe it is falling back in the tank and I have to crank it until it gets fuel back to the carb. is there some kind of check valve that goes on the end of the fuel line in the tank? I pulled my fuel line out of the tank and there is nothing on my line. I shouldn't have to crank it until the line fill back up every time. fuel pump is also new. any suggestions? or maybe a illistration of the fuel tank assy. thanks mike

 

[mllud]

Chech that tube that goes down into your tank for small holes or splits. That causes fuel to fall back into the tank.It also causes a vacume leak and makes it harder to draw the fuel up. A loose clamp can do the same thing. Mike

 

[drdent]

Chech that tube that goes down into your tank for small holes or splits. That causes fuel to fall back into the tank.It also causes a vacume leak and makes it harder to draw the fuel up. A loose clamp can do the same thing. Mike

I will recheck the hose,but it seems there should be something on the end of the hose to keep the fuel in.I was wondering if a check valve or filter belongs there and fell off into the tank. or is it just a hose? I was thinking of putting on an electric fuel pump, but wasn't sure how to regulate the pressure or if the float in the carb would be enough. mike

 

[drdent]

I will recheck the hose,but it seems there should be something on the end of the hose to keep the fuel in.I was wondering if a check valve or filter belongs there and fell off into the tank. or is it just a hose? I was thinking of putting on an electric fuel pump, but wasn't sure how to regulate the pressure or if the float in the carb would be enough. mike

I don,t bother asking our local dealer because they get an attitude because I want to fix it myself. (which I understand, they get nothing for schooling me). that's why I like this forum.I buoght a service manual last year. it was well worth the money, but there is no break down of the fuel system that shows the end of the fuel line. mike

 

[Tazza]

I don,t bother asking our local dealer because they get an attitude because I want to fix it myself. (which I understand, they get nothing for schooling me). that's why I like this forum.I buoght a service manual last year. it was well worth the money, but there is no break down of the fuel system that shows the end of the fuel line. mike

I know the carb is new, but could it be as simple as being a problem with your choke?
I agree it sounds like a fuel problem. Can you remove your fuel line to the carb after the fuel pump. Crank the engine and ensure you have fuel pressure.
The other way is to setup a temporary fuel tank, sit it up on the oil cooler or something so gravity will help provide a bit of pressure to the carb and see if it starts easier.
Did you replace the ignition coil too?

 

[mllud]

I know the carb is new, but could it be as simple as being a problem with your choke?
I agree it sounds like a fuel problem. Can you remove your fuel line to the carb after the fuel pump. Crank the engine and ensure you have fuel pressure.
The other way is to setup a temporary fuel tank, sit it up on the oil cooler or something so gravity will help provide a bit of pressure to the carb and see if it starts easier.
Did you replace the ignition coil too?

Tre isnt usually a check valve down in the pick up tube. You should have enough fuel left in your carb. bowle to restart or fire some even after sitting. Like Tazza said I would take a good look at the choke and make sure it closes good. New carbs can have loose screws. I would also check the vacume lines.If you could have somone cup the top of the carb when its cold and you crank that would answer the choke question. Mike

 

[73Eldo]

Tre isnt usually a check valve down in the pick up tube. You should have enough fuel left in your carb. bowle to restart or fire some even after sitting. Like Tazza said I would take a good look at the choke and make sure it closes good. New carbs can have loose screws. I would also check the vacume lines.If you could have somone cup the top of the carb when its cold and you crank that would answer the choke question. Mike

Like others have said its somewhat normal to loose all the fuel in the lines and pump back to the tank after sitting for a while. Reason its not an issues is the carb should still be full which should get you started and run for 10 seconds or so which should be plenty long to get the pump primed and full again. What kind of carb does this have? I assume an autolite 2bbl? Looking at the top of the carb where the choke butterfly is there should be tube that is about 1/4" in diameter that points twards the bowl area (could be directly below it ). When you know you are going to have the problem try carefully pouring some fuel down that tube. The tube should be the bowl vent so what you will be doing is filling the bowl. No big deal if you spill a little down the throat, that will burn off quickly also. A small bowl is 1"x1". Some of the autolites were 2"x2" so they will hold a lot of gas. If you can get a carb model number I can ask some of the gurus on other sites what their problems are. I know mostly rochesters and 1bbl autolites.

 

[jerry]

Tre isnt usually a check valve down in the pick up tube. You should have enough fuel left in your carb. bowle to restart or fire some even after sitting. Like Tazza said I would take a good look at the choke and make sure it closes good. New carbs can have loose screws. I would also check the vacume lines.If you could have somone cup the top of the carb when its cold and you crank that would answer the choke question. Mike

The 642 must be different than our 632, on mine the fuel line exits the tank on the bottom and then halfway to the engine there is a electric solenoid valve that shuts off fuel flow when the key is off. Like Tazza said, check the ignition also especially the vacuum advance to make sure you are not losing vacuum through a bad diaphragm.

 

[jerry]

The 642 must be different than our 632, on mine the fuel line exits the tank on the bottom and then halfway to the engine there is a electric solenoid valve that shuts off fuel flow when the key is off. Like Tazza said, check the ignition also especially the vacuum advance to make sure you are not losing vacuum through a bad diaphragm.

Like the others said also the choke on that engine is extremely fussy if it doesn't close completely it won't start.

 

[Tazza]

Like the others said also the choke on that engine is extremely fussy if it doesn't close completely it won't start.

I was told that bad coils can do this as well, I'm pretty sure i was told the spark should be blue and not orange. If its orange you have a problem with points/coil.
I hope you get it all sorted out!
These are the times I kinda like diesels, if the injection is rite and there is fuel you are pretty well guaranteed it will work.

 

[sterlclan]

I was told that bad coils can do this as well, I'm pretty sure i was told the spark should be blue and not orange. If its orange you have a problem with points/coil.
I hope you get it all sorted out!
These are the times I kinda like diesels, if the injection is rite and there is fuel you are pretty well guaranteed it will work.

does it have the electric shut off? if so try bypassing it and see if its better, and do you shut the fuel off with the valve on the tank? try opening that valve and wait 5 before trying to start...gravity "should"fill the line and pump .if you go electric make sure it is for a carb not injection different pressures you know..........Jeff