hard start when hot

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clemon

clemon

Well-known member
Joined
May 15, 2012
Posts
279
Location
Kitchener, Ontario Canada
Hi folks,

Thought I'd post this question now so I can be ready for the warm weather when it finally arrives! 

Last season, my 1992 Southwind 30 consistently was hard to start when hot - ie after driving for a while. We'd pull into a gas station, stop the rv, fuel up and have difficulty getting the rig started again. If we sat somewhere long enough for the engine to cool a bit, no problem. When I needed a hot start (ie at the fuel pumps!), I usually ended up shutting off any 12v accessories running at the dash (fan blower, radio etc) and hitting the battery switch to connect the chassis battery and the house battery bank. This would do the trick, though it could take an embarrassing amount of cranking to turn the engine over.

The dealer did replace the starter motor at the beginning of the season, and the engine got a full tune-up with plugs, wires, and distributor cap.

Any ideas? The battery seems to charge and hold charge just fine, but I can't quite figure this out. Any insight from those with more know-how is greatly appreciated. I'm afraid that if I don't get this sorted out, my wife will kybosh any longer trips this year :(

 
Hi Charles I would assume she is fuel injected. I would focus my search on the coolant temp sensor for the computer. Chevys have 2 temp sensors. one runs the idiot light or gauge and the second runs the computer which is in charge of injecting the proper fuel air mix. These are a common failure at the age we are talking.
The computer belives the engine is cold so she dumps extra fuel in to start the "cold" engine in turn flooding the hot engine. If the engine starts cold with no issue that would be my first stop.
 
commkruge - thanks for the info! I'll pull the manual from the rig next time I'm at the storage lot and take a look for those sensors. If I'm lucky they're something I can replace myself  :)
 
Charles,
They are fairly easy to get at. One is normally on the thermostat housing and the other at the back of the motor will have to pull dog house depending on which one runs what.  Was meaning to ask once it starts does it puff a bit of smoke and clear up once ran a couple minutes? If it does she was flooded...
 
Do you have a heat shield on the starter? It gets real hot down there....

Dan
 
commkruge said:
Charles,
They are fairly easy to get at. One is normally on the thermostat housing and the other at the back of the motor will have to pull dog house depending on which one runs what.  Was meaning to ask once it starts does it puff a bit of smoke and clear up once ran a couple minutes? If it does she was flooded...
Click to expand...

This does seem familiar! Rough start, puff of smoke then ok, IIRC.

I've sent myself a note at home (I'm currently at work) to follow up. The reassuring thing here is that while I'm not the most mechanically inclined when it comes to engines, my neighbour is a Class A mechanic who'll help out for a cold beer!  :D

 
dan2 said:
Do you have a heat shield on the starter? It gets real hot down there....

Dan
Click to expand...

Hi Dan. Not sure about the heat shield but will definitely check it out. I know the floor around the doghouse can get quite warm running down the road, especially on the passenger side (I did remove the carpet and underpad in favour of vinyl laminate, which removed a few layers of "heat shield". May have to remedy that this spring too!).
 
There are two "Hard to start" conditions I will describe.

ONE: Cranks normally, won't fire. 

Two: Very slow cranking (if it even cranks at all)

The first can be vapor lock, though modern vehicles are designed to minimize that posiblity I'm told it still happens. . It can also be an oil pressure switch and bypass relay.. ON SOME engines (GM works this way) the in-tank electric fuel pump is controlled aby an oil pressure switch, There are assorted reasons for this but if you should, for example, roll it over, this switch will loose pressure and cut off the fuel flow. (Very good design).. But if your engine is worn and loosing pressure when hot, it won't turn the pump on,, had this problem...  There is supposed to be a bypass relay that engages the pump when cranking, but alas, It too failed in my case.

The second problem (Slow craking acts almost like low/dead battery) may require a sdtarter replacement. Happend to me several times in the last nearly half century different cars.
 
Hi John. Thanks for the input. I do wonder about the starter; I would not be at all surpised if the dealer I used for the work subbed in a used starter, as the work was done on their dime, not mine. Not using them anymore (surprised, aren't you?  :D)

I plan to have all of this looked at first thing after getting the rig out of storage this spring - now all I need is warm weather!

 
grounds, engine ground. battery ground frame ground . any ground that should be grounded NEEDS to be cleaned. BOTH ends of the cable.
last summer I was having the slow crank problem and cleaned all of the grounds found one off at the rear of the engine. used everything was electrically tight she fires right up.

You can not just look at them either the connections to the little solenoid looked perfect. but when I took them apart there was virtually no contact there.

Just something else to take a look into. :)
 
clemon said:
now all I need is warm weather!
Click to expand...

Gee, Most of the Eastern US was above 40 this morning if the radio reports are to be believed,,  A few in the 30's but I don't think anyone was freezing.

Back when I lived in Detroit,, I recall this time of year where 30's and 40's were not all that uncommon... only there was a MINUS sign in front of the temp.
 
Your starter becomes heat soaked. 454's, air-cooled VW's and old Fords do this. 1st, check for exhaust leak around manifold, particularly underneath the manifold, above the starter.  You can use a piece of garden hose like a stethiscope. Don't aim it in your ear, just hold it near. You'll know a leak when you hear it. Has to be fixed for 100% satisfaction.
Or shade tree style, go to a town dpw barn. Explain you need to fabricate a heat shield and was wondering if they had an old, run over, ruined stop sign, or something. Take it home and with a jig saw, a drill and some nuts and bolts fabricate your own. Tempered aluminum street signs make great heat shields, I've made more than 1 over the years. 8)

Bill
 
I don't think the OP has defined his problem well enough to say it is starter related.  The only indication was that he turned everything off and jumped the house batteries in so he could crank it long enough to start.  We still don't know if the starter is dragging or if he just needs the extra juice to be able to crank long enough.  If the problem is starter overheating then it would be an obvious dragging problem.  On the other hand, it the starter cranks just fine, but eventually pulls the battery down, it's most likely fuel supply related.  It may need a heat shield for the fuel line and not the starter.
 
OP states he had to give himself a jump start with the button Having said that, I deduce it' s cranking slow. Starter has been replaced already by another shop. I would take that to mean that shop was trying to fix a slow cranking starter when hot. Classic symptoms and wrong fixes. Been there done that.

Bill
 
driftless shifter said:
OP states he had to give himself a jump start with the button Having said that, I deduce it' s cranking slow. Starter has been replaced already by another shop. I would take that to mean that shop was trying to fix a slow cranking starter when hot. Classic symptoms and wrong fixes. Been there done that.

Bill
Click to expand...
Guess I don't read it the same way as he also says he still has to crank a long time.  I deduce that to mean he needed the extra battery not to crank it, but to crank it long enough.  The OP will have to clarify this, I think.
 
Grounds have already been adressed here, but could be the problem as the starter has already been replaced. Is this coach injected or carburated? The GM quadrajet was known for leaking well plugs. Does it have to crank a bit when cold also? If the well pkugs are leaking, it'll flood the engine when filling up a rv tank. My old 77 T/A used to do that. Classic car, out driving on a nice Sunday afternoon. Every time I shut it down and restarted a few minutes later it'd do the same thing. Blow black smoke for a bit and clean up. If it's carbed, look into the well plugs.
 
Hey folks. Thanks for all the replies - I'm not sure I expected this much interest in a rig in storage, so thanks!  :D

For the record, my 454 is injected, not carbed. I will have my mech look at the starter and the coolant temp sensors during my Spring wake-up tune-up, and hopefully have another great season with the old beast! We've not owned the rig long, but already even the kids miss having it in the driveway (though I must admit my wife appreciates the storage lot!).

Hopefully hitting the London, ON RV Show this weekend to drool and dream of getting away from it all again soon.

Thanks again,

Charles
 
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