Engine starting mystery

[stevenelle]

218 in B2B starts up every morning without problem (using some choke and some extra throttle). If it is driven far enough to get good and hot, then the subsequent re-starting while still hot does something weird: If I am in the store only 5 minutes or so, it starts right back immediately. But if I am in the store for 30 minutes or so, then it is very hard to re-start. It finally does start, but it takes a long time of cranking. I am wondering what may be going on. I have re-routed the fuel line so that it is at least 4 inches away from the manifold. I do not have a heat shield in place for the fuel pump. Thanks for anyone who can advise on what might be going on and what might be done to improve this situation.

[Norm's Coupe]

You could be having a slight vapor lock problem since you don't have a heat shield.

Another possibility is the same problem I had right after getting my coupe back on the road. It's a very simple problem and easy to fix. It could be a problem with the operator. We are so use to the way our modern cars operate, we have to train ourself all over again. For example: When first starting cold in the AM, you have to pump the gas up into the carb. and use the choke. However, after driving the car/truck, it's not necessary to pump the gas to the carb. If the car/truck has only sat for about 30 minutes after running and getting warm, it's also not necessary to use the choke. Then there are times where the car/truck may have sat long enough (a few hours) after running, you may only need to pull the choke out part way, not as much as you did on the first start up for the day.

Each time I make some change to the fuel system, or give the car a tune up I now retrain myself in the starting procedure for my coupe. I do this in the driveway so I know just how it will react if I'm on the road later.

I grew up around these cars and learned how to drive on them as a kid, so you'd think I wouldn't have to retrain myself. However, like I said, after driving the modern cars for so long, we sometimes forget.

[MBF]

I had this same problem w my '36 Plymouth-started great cold-not so when hot. Check to make sure you have good clean connections and heavy enough cables from the battery to the starter switch, and have a GOOD ground directly from the battery to the starter mount bolts. If all of these appear to be ok, you may want to check the starter amp draw-may be drawing to heavily and starving the ignition system for current. I take the dust band off my starter every once in awhile and clean up the commutator with a dressing stone. You could also have a problem with the gas boiling in the bowl of the carb as it sits after a run-this could especially be true if the heat flapper is stuck in the closed position. I eventually converted it to 12v because I couldn't find a 6 volt batt that lasted more than the warranty period. Mike

[grey beard]

May we assume you are speaking about hard starting when hot - and NOT hard cranking? Is this an electrical/cranking issue or a won't-start-when-warm issue?

If it franks slowly when hot, take Mr. Fowler's advise above - sounds like a poor ground or a cable problem to me.

If it cranks normally but will not start, I would suspect a "hot soak" problem, where the fuel in the line expands and pushes the float down in the bowl, essentially flooding the poor thing while it sits there doing nothing. To check for this problem, next time you start it hot as you described, slowly floor the throttle and hold it in wide open position. With the throttle wide open and NO choke on, try cranking it, and see if it will clear itself out. This will prove whether or not the issue is fuel related.

When engines hot-soak, and you attempt to start them without any throttle applied, the throttle plate acts just like another choke plate, and makes the mixture even more richer.

One fix for this is a new needle valve and seat in the carb. This is inexpensive and can be done easily with the carb on the engine - worth a try. You'll need to readjust the float when you're finished installing the valve. Econoline six cylinder engines used by Sears for applicance repair had this problem when I was a Ford service rep, and we had to replace the needle valve and seat with a Gross Jet ball and seat that held more pressure from the expanding gas in the fuel line. Usually a new needle valve and seat will cure the issue, though. JMHO:)

[greg g]

My theory is that for summer hot temp driving the factory float spec is to high. I have lowered mine to address hard start when hot problems. The theory goes like this;

You shut your car off, and the float bowl is full of gas. As the car sits, the bowl is subjected to the heat rising from the exhaust manifold. Being that todays fuel is more volitile (expands and evaporates at lower temperature)than earlier distillations, the fuel in the bowl expands overflowing the float chamber and dumping raw gas down the carb throat, where it puddles in the manifold. Then because the level goes down, the float opens allowing residual pressure in the line to refill the bowl. It then begins to expand and over flow again. If this cycle repeats itself a few times you have a very wet intake manifold which floods the engine at restart attempt. I believe a slightly lowerd float setting effects this positively as it maintains the fuel lower in the bowl leaving more room for expansion without overflowing.

So next time you try a hot start, do not pull the choke, do not pump the gas pedal, instead, slowly floor board the gas pedal and hold it at WOT while cranking the engine. If your engine starts better using this method, I believe my theory is supported, as the extra air at WOT will help disapate the raw fuel in the manifold.

If this helps, the try resetting the float level. All you need is a screwdriver and needle nose pliers.

[greg g]

Hey Dave, we must have gone to the school of redundancy school together. I did work in the department of redundancy department for a while.

Some would say that great minds think alike, while other would suggest that fools seldom disagree. Good not disagreeing with you.