Rough Starting

rwbow1969 · Post by **rwbow1969** » Thu Jun 23, 2011 1:01 pm

Hello, I was wondering if anyone else has experienced this problem. When I drive my M38 for lets say 10 miles or so and park, I shut the motor down, run into the store, come out and it seems like a struggle to start. When I first start it up in the garage it starts immediatly on first crank. Could this be due to not letting it idle out a little before shutting the motor off. This just occurs after running for a while and then restarting in a few minutes.

Thanks, Rob

RickC · Post by **RickC** » Thu Jun 23, 2011 8:41 pm

I was wondering same thing. Doesn't happen if it sits for a while right?

Post by **wesk** » Thu Jun 23, 2011 9:31 pm

Engines heat soak right after they are shut down. The reach their highest temps in that first 30 to 45 minutes after shutdown. A healthy jeep will start just fine during those super heated periods but let something be week or mis-adjusted and she can be a bear to start.

The common performance issues that will really rear their head during this super heat period are:

Mis-adjusted ignition timing.
Weak ignition coils
Weak capacitors and condensers
Tired plugs or plugs with a lot of electrode wear causing a larger gap.
Points with a lot of wear and pits.
Tired spark plug leads. The heat tends to cause them to leak when they are old.
Manifold heat risers that are broke or sticking on L134's will boil the carb's bowl dry during these super heat periods.
Fuel lines from the pump to the carb that are too close to the exhaust manifold will vapor lock.
Tired starters will not spin the engine as fast when hot.

rwbow1969 · Post by **rwbow1969** » Thu Jun 23, 2011 9:43 pm

Thanks Wes, I appreciate your answer. I will have something to go with now

Rob

artificer · Post by **artificer** » Mon Jun 27, 2011 2:24 am

Wes offers a good starting point although often in HOT weather:-
Also it is possible for the fuel to boil & flood the engine, plus too high fuel pressure can contribute as there is still pressure in the line between the pump & carburettor so when the fuel boils new fuel opens the needle valve entering the float chamber & so on. Carburetors usually have an anti percolation valve to alleviate this flooding issue so this might be where to start.

RickC · Post by **RickC** » Mon Jun 27, 2011 7:21 am

I had thought about that but the problem with mine is it barely cranks over...like the batteries are dead.
Rick

DJ · Post by DJ » Mon Jun 27, 2011 8:09 pm

When did you last change oil,and what oil is in it?

Post by **wesk** » Mon Jun 27, 2011 10:22 pm

I had thought about that but the problem with mine is it barely cranks over...like the batteries are dead.
Rick

Then you should start here:

Tired starters will not spin the engine as fast when hot.

A-Are batteries in good shape?
B-Are all terminals clean, corrosion free and tight.
C-Is the heavy ground strap between the frame and the right front engine mount there? Clean, corrosion free and tight?
If A,B & C are OK consider removing the starter and having it bench checked at a good auto electrics shop.

Is the timing correct. Too far advanced and she will often start reasonably well cold but create the slow turning starter symptom when hot. I don't mean timed ok by ear. Ear timing by folks without a lot of experience can often end up at 10 or 12 degrees BTDC simply because the engine sounds really good there and the vacuum reading will be really good but starting suffers once you get up past 7 Degrees BTDC.

RickC · Post by **RickC** » Tue Jun 28, 2011 5:00 am

THanks Wes. New batteries and everything else fine..... Looks like I'll be checking the starter......
Rick

RimfireJim · Post by **RimfireJim** » Tue Jun 28, 2011 6:57 pm

I had a '77 Ford F-150 that wouldn't crank when it was hot, and the root cause was an undersized aftermarket positive battery cable. Replaced it and never had another problem with that. Confirmation of Wes' points about the importance of good electrical connections and cables.

I also had (well, still have it) a '53 Ford F-100 that had a rebuilt starter on it at one point. Developed a poor cranking attitude. Root cause turned out to be too thin commutator bars on the starter motor which couldn't conduct enough current. Another rebuilder said it should never have been turned down that far. They rebuilt it and all was well.