Hot start issue...

[Oshkosh1]

So I'm out today, ran around for about 20 miles then decided to stop and swim. We pulled in to where we THOUGHT it would be good, but found out it was weedy. I said, no problem and figured we'd move about 200 yards closer to some more boats and went to start(after sitting for about 2 min). Cranked and cranked...but didn't fire. Waited about 10 min then went to start and it fired up with a little bit of throttle work.

When cold, it starts without touching the throttle, and within 1 rev...

I also noticed that the idle is a little rough when hot, again, "cold"(on muffs) it has no problems.

It jumps out of the hole, and has no problems with power, but does stumble a bit when just coming off idle.

I'm thinking the choke is not set correctly, or when I set the mixture/idle it wasn't warmed up enough and set it incorrectly???

The carb was rebuilt professionally(Autoline in Canada). Has less than 5 hours on it.

FULL tune-up done...cap/rotor/wires/plugs/coil/timing set -8BTDC/dwell at 30deg. Idle was set @600RPM, and vacuum test at manifold was 20" at idle. Idle mix screws are 3/4 turn out from stop. Compression was about 135 across the board, valve lash set @0+3/4 turn.

Thanks in advance for the replies...

 

[Oshkosh1]

Re: Hot start issue...

Bump...

 

[Bondo]

Re: Hot start issue...

Bump...

Ayuh,... WHEN it don't start,... LOOK to see if it's lackin' Fuel, or Fire....

 

[Oshkosh1]

Re: Hot start issue...

It's getting both...

It DOES start...just not nearly as easy as it does when cold.

I could walk out there right now...and it would fire up almost quicker than I can release the key. No pumping, no hesitation, holds idle @ a rock solid 600RPM.

One pump of the throttle and I get a nice squirt of gas. There was a very slight "gassy" smell...however I just chalked that up to normal "fumes". Not overpowering like when flooded.

I don't stare down carbs while starting. I was looking down one in about 1984 when it "flashed"...that was enough for me.(69 Charger...Holley 850...lost half my eyelashes!)

 

[Oshkosh1]

Re: Hot start issue...

After reading some on vapor lock conditions...I'm seeing alot of similarities. Either that or the fact that this carb sits directly over the exhaust manifold I could have an issue with the fuel in the bowl boiling after shutdown. Seems to be an issues with older carbed cars in hot conditions where heat is built up under the hood under "stop and go" conditions.

Maybe adding more venting in the engine compartment?

Has anyone had luck using a phenolic spacer to raise the carb, insulating the fuel lines, or fabricating a sort of heat shield to keep the carb a little cooler?



I've got rubber fuel line from the tank to F/W seperator. Rubber from F/W sep to pump. Metal for 8" vertical from the pump, a 45deg bend for 2", then rubber spliced where it bends around and over the fwd part of the valve cover to the carb...with an inline filter installed about 4" fwd of the carb.

 

[Bondo]

Re: Hot start issue...

Metal for 8" vertical from the pump, a 45deg bend for 2", then rubber spliced where it bends around and over the fwd part of the valve cover to the carb...with an inline filter installed about 4" fwd of the carb.

Ayuh,... It's Supposed to have a solid metal line from the pump to the carb, WITHOUT an in-line filter...

Are ya givin' it plenty of Throttle when yer tryin' to start it,..??

 

[Oshkosh1]

Re: Hot start issue...

I give it about 1/2 gas...

I was wondering about that fuel line setup...not my design, the PO....well I did add the inline filter after reading about the problems with the tiny filter in the carb getting clogged. It's a 3"metal/glass, replaceable plastic mesh element, see-through type.

 

[Bondo]

Re: Hot start issue...

I give it about 1/2 gas...

I was wondering about that fuel line setup...not my design, the PO....well I did add the inline filter after reading about the problems with the tiny filter in the carb getting clogged. It's a 3"metal/glass, replaceable plastic mesh element, see-through type.

Ayuh,... It's a Bomb,... Get rid of it,... You've already got a canister style...

 

[Oshkosh1]

Re: Hot start issue...

Ayuh,... It's a Bomb,... Get rid of it,... You've already got a canister style...

Very well...

What is the correct size metal liine to use?

 

[Bondo]

Re: Hot start issue...

Very well...

What is the correct size metal liine to use?

Ayuh,.... 3/8" steel brake line uses the same fittings...

 

[Don S]

Re: Hot start issue...

Does your engine compartment get real hot inside when the engine is shut off after a good run? If you suspect vapor lock, take the boat for a run, and stop like you normally would, only open the engine hatch and let the air in. Then see if you still have the starting problem.

After you get your fuel line fixed, and the engine is cold. Open the throttle about 1/8 to 1/4 throttle. Then adjust the choke until the choke plate just closes, or maybe one notch tighter. The manual makes them really tight and they close the choke when the engine is still warm, but the choke coil closes up to early.
Then run the engine until warmed up completely and adjust the idle mixture.

Does the engine ever diesel when you shut it off ?

 

[Oshkosh1]

Re: Hot start issue...

I think I've got a bender...not sure about a flare tool though.

Any other ideas regarding the starting issue? I'm guessing the fuel line, while not correct is not the sole culprit.

 

[Oshkosh1]

Re: Hot start issue...

Does your engine compartment get real hot inside when the engine is shut off after a good run?

Yes

If you suspect vapor lock, take the boat for a run, and stop like you normally would, only open the engine hatch and let the air in. Then see if you still have the starting problem.

Wilco

After you get your fuel line fixed, and the engine is cold. Open the throttle about 1/8 to 1/4 throttle. Then adjust the choke until the choke plate just closes, or maybe one notch tighter. The manual makes them really tight and they close the choke when the engine is still warm, but the choke coil closes up to early.
Then run the engine until warmed up completely and adjust the idle mixture.

I will check it this afternoon

Does the engine ever diesel when you shut it off ?

No

 

[captk]

Re: Hot start issue...

You should also check the voltage at the coil while cranking hot.

 

[Oshkosh1]

Re: Hot start issue...

You should also check the voltage at the coil while cranking hot.

I checked it when I was installing the required resistance wire...Just wondering why it would be different hot? Would that be a battery issue? It's a Marine deep cycle battery.

I'll check the cranking voltage again when it's hot.

 

[Oshkosh1]

Re: Hot start issue...

You should also check the voltage at the coil while cranking hot.

Ok...checked the voltage...9.6V. Seems low...temp was only 80deg. I think the battery may be an issue.

Open the throttle about 1/8 to 1/4 throttle. Then adjust the choke until the choke plate just closes, or maybe one notch tighter. The manual makes them really tight and they close the choke when the engine is still warm, but the choke coil closes up to early.
Then run the engine until warmed up completely and adjust the idle mixture.

Also, checked the choke, and adjusted it as per above.

 

[Don S]

Re: Hot start issue...

Ok...checked the voltage...9.6V. Seems low...temp was only 80deg. I think the battery may be an issue.

Do the same test cold.

 

[Oshkosh1]

Re: Hot start issue...

Do the same test cold.

I'm afraid that's as "cold" as it's gonna get...boat was in a garage and out of the sun, sitting cold iron for 15 hours. It MAY get down to the 70's at night, but no less for the next week.

I should probably take it to the local NAPA and have it load tested.

 

[Oshkosh1]

Re: Hot start issue...

Took the battery to get tested...
Out of the 500CCA it was rated for, it showed 116, 13.8volts and a bad cell. So it's time to look for a battery.

 

[dollarten]

Re: Hot start issue...

As hot and humid as it's been lately I have have been having the same problem with a collector car I recently got running . Got gas and spark and no run . Wait awhile and the it will start . I had similar problems with a 120 Mercruiser What I am thinking is that the 87 octane gas blended with ethanol we now have is for fuel injected engines This modern day fuel will loose some of it's volatility when it sits in a carburetor bowl where some of it's properties evaporate and will not ignite until till it cools off or the carburetor bowl gets refilled with the fuel not exposed to atmosphere I am no scientist but . I think the ethanol in modern day fuels does not bode well in carburated engines I switched to no ethanol gas and had no further problems wit the 120 Should have know better wit the collector car