Guest Dan Karczewski Posted August 2, 2011 Share Posted August 2, 2011 OK,, I need help trying figure this one out on my car, if I had hair I would pull it out.I took my 1938 Pontiac 6 cly. in the 4th of July parade and it ran OK , even had it going 55 MPH,, but it had some hesitation like it was not getting enought gas.Well few years ago I had the fuel pump rebuilt and it had not been driven in a long time. I thought that maybe the diaphram was no good any more.So I had it rebuilt again, well how the car after about 10 minutes of driving would "lunge "back and forth " like it was not puming gas to the carb.I do have a fuel filter between the Carb. & fuel pump and notice that there was some sand in the filter. So I had the Carb. rebuilt.Put it back on the car still same old thing after about 10 minutes of driving it would jerk like no gas was getting to the carb. The car would even quit running some times.List of things I done so far to make it run better ,but no luck.1.) rebuilt fuel pump2.) rebuilt carb.3.) blew out all gas lines and made sure the connection were tight4.) drop gas tank off and it has been sealed, nothing in the tank.5.) Gas filters replaced, have one before the fuel goes into the fuel pump and also one before it goes into the carb.6.) check and made sure the manifold heat control valve was working.7.) put premium gas in, it was suggested to use the better.8.) added gas additive to get rid of surging & stalling.STILL my car after about 10-15 minutes of driving still surges and stalls out, when this happens I try to get to the side of the road so I do not get hit. After about 10 minutes of cooling down it will start up again and I pray I make it back home. I would like to drive my car this summer more than just around the block which I have been doing every time I try new steps to find out what is wrong,,,, "ANY HELP IS WELCOME" It had gotten worst after I had the fuel pump rebuilt, maybe I should of left it alone, but I wanted to tweak it ,so when it was going 55 mph it would not hesitate.Another thing it can idle in my drive way for 20 minutes and it runs like a swiss clock, HELP going MAD. LOL:o Link to comment Share on other sites More sharing options...
MCHinson Posted August 2, 2011 Share Posted August 2, 2011 I am not familiar with 1938 Pontiac's engine compartment. Does the fuel line run near the exhaust manifold or some other high heat source? Sounds like it could be fuel vaporization in the fuel line due to heat. Others have solved similar problems by rerouting fuel lines and/or insulating fuel lines.If you have a local source of non-ethanol gasoline, I would suggest trying that. I suspect that non-ethanol fuel would behave differently in your car, and might solve the problem. Link to comment Share on other sites More sharing options...
Matt Harwood Posted August 2, 2011 Share Posted August 2, 2011 Could be something unrelated to fuel? A bad coil can sometimes act like a stuttering carburetor, especially when it's heat-related (fine when cold, problems when hot).Just another path of thinking anyway. Hope it helps. Link to comment Share on other sites More sharing options...
Guest Dan Karczewski Posted August 2, 2011 Share Posted August 2, 2011 Thanks for the advise, I did move the fuel lines as much as I could away from heat source. I will start with adding some fuel line insulation.If that does not work, then I will replace the coil, it is the original one anyway. I did replace the dist. cap and rotor, changed the spark plugs also.FUN FUN FUN. Thank you DAN. Link to comment Share on other sites More sharing options...
W_Higgins Posted August 4, 2011 Share Posted August 4, 2011 Replace the coil. That's almost certainly the issue. Link to comment Share on other sites More sharing options...
unimogjohn Posted August 4, 2011 Share Posted August 4, 2011 and don't forget that condenser in the ignition circuit too when you replace that coil. If its gets hot and is old, it will act like you are running out of fuel too. Link to comment Share on other sites More sharing options...
Restorer32 Posted August 4, 2011 Share Posted August 4, 2011 And please report back. Link to comment Share on other sites More sharing options...
Guest 36chev Posted August 4, 2011 Share Posted August 4, 2011 As John stated the condenser could be a suspect. One time thought what was a carburator problem turned out to be a failing condenser. Points were burned by the condenser not condensing, so if this is it might think about replacing them. Link to comment Share on other sites More sharing options...
Guest LarryB Posted August 4, 2011 Share Posted August 4, 2011 I was going to suggest the condenser too. Just replaced all the wires, points, cap and distributor this year. Had it running good and then went back in to adjust the points again and some how losened the condenser. Car would run, but hesitate and after a few minutes would stall-out. Check that all your wires are tight. Link to comment Share on other sites More sharing options...
Guest Bandit305 Posted August 4, 2011 Share Posted August 4, 2011 Check the gas cap too, make sure the vent is open. Link to comment Share on other sites More sharing options...
Guest Al Brass Posted August 4, 2011 Share Posted August 4, 2011 Hi Dan,It seems to me there is a lot of guessing going on. Start by checking the fuel system. Find a quiet road somewhere close by and drive your car until it stops. Leave it stopped and then check the carb bowl to see if it has starved for fuel. If you rule fuel problems out, it should make finding ignition issues easier.RegardsAl Link to comment Share on other sites More sharing options...
Guest Dan Karczewski Posted August 6, 2011 Share Posted August 6, 2011 UPDATE: This morning I replaced the condensor since I found my small wrenches for it.Drove it for about 30 minutes without a problem ran like a swiss watch. Then there was some hesitation but it did not stall out and on the way home about 8 miles away had just a few more hesitations. So I thought it was going to be a easy fix with just the condensor. Well I went to my local antique auto parts store Northwesternautosupply.com and they had a coil for me, we tested the newer coil at the shop and it was good. So I installed the new one. Took it for a drive for about 15 minutes and then it started to jeck and this time I had to pull over on the side of the road. Unlike this morning I did not have to pull over. So my next movewill be going to wrap the fuel lines with insulation. I guess GOD is testing my patience. Dan the Pontiac Man. Link to comment Share on other sites More sharing options...
Guest Julian Posted August 9, 2011 Share Posted August 9, 2011 Find a quiet road somewhere close by and drive your car until it stops. Leave it stopped and then check the carb bowl to see if it has starved for fuel.Had a very similar issue with my 42 Olds. It did just as described. My mechanical fuel pump just could not keep the carb supplied at modern high way speeds. I put an electic fuel pump on it to supply the mechanical pump. Checked the fuel pressure at the carb and was good. Fixed my problem. Link to comment Share on other sites More sharing options...
19tom40 Posted August 9, 2011 Share Posted August 9, 2011 Let your car get to normal operating temperature and then check the spark at idle. It should be the same intensity that it when the coil is cold. Take it for a ride, if you get hesitation, recheck your spark. I like to see 1/2 inch blue spark when idling.A new coil is not a guarantee of a good spark, especially if it is a NOS coil. The insulation breaks down under heat and they arc internally. Link to comment Share on other sites More sharing options...
Guest Al Brass Posted August 9, 2011 Share Posted August 9, 2011 UPDATE: So my next movewill be going to wrap the fuel lines with insulation. I guess GOD is testing my patience. Dan the Pontiac Man. Al said there is a lot of guessing going on. Start by checking the fuel system. Find a quiet road somewhere close by and drive your car until it stops. Leave it stopped and then check the carb bowl to see if it has starved for fuel. Why are you contemplating wrapping fuel lines when you don't know your problem is fuel? Doesn't make sense to me :confused:Al Link to comment Share on other sites More sharing options...
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