5.0 V8 does not start easily when it is warm

[fsamie1]

my 1989 5.0L V8 starts good when cold. But, when it is warmed up to about 170 F, it starts very hard. I have to open throttle ALL the way and crank it for about 8-10 seconds before it starts. Whe it starts, it runs sluggish for a few second and then it is fine. I tried to start it with different amount of priming and this did not help. I have to open throttle 100 percent. I also tried to run it in idle for 5 minutes before turning it off, it did not help.
There is no problem in the driveway hooked up to garden hose, it starts fine when warmed up in neutral. I checked spark and it good. It was ok last year and water temperature was 160 F. This year, it is about 170 F and it is the same when running idle or high speed.
Any help is appreciated if you think it is vapor lock, how do I fix it? I am going to try a new 160 thermostat and then 140 thermostat.

 

[DHPMARINE]

Re: 5.0 V8 does not start easily when it is warm

Your temp gauge maybe off,but 170 is on the hot side.Especially with todays gas.

I'd be trying to get the temp down (last water pump impeller?)

The 5 minute idle is a good idea,but a 5 or 10 minute slow cruise maybe more benificial.

DHP

 

[fsamie1]

Re: 5.0 V8 does not start easily when it is warm

Thanks DHP, I put in a new 140 thermostat and ran it with garden hose for 30 min. at 1200 rpm idling. Water temp got to 160 which is about 10 degree lower than before. I am taking it out this weekend to see if it starts easier after 3-4 mile run. Any idea why engine starts hard when it is a little warmer than 160? Same engine runs about 200 F in cars.

Samie

 

[John_S]

Re: 5.0 V8 does not start easily when it is warm

I'd check if the choke is openning fully when engine is warm. If you smell the oder of gas after shutdown, the carb is probably leaking into intake causeing a very rich/flooded condition, that requires the throttle to be opened fully, to clear.

 

[THE BEEF]

Re: 5.0 V8 does not start easily when it is warm

You might want to watch down the carb after you shut it off warm.
Don't open the throttle and see if any fule is dripping off the jets.
If you have a black plastic float on that carb it might be going bad (sinking
lower) in the bowl causing fule to leak down in the manifold causing hard starting. Yes they do get saturated with gas and lower.
Just a thought, Im no expert
Beef

 

[Bondo]

Re: 5.0 V8 does not start easily when it is warm

You might want to watch down the carb after you shut it off warm.
Don't open the throttle and see if any fule is dripping off the jets.
If you have a black plastic float on that carb it might be going bad (sinking
lower) in the bowl causing fule to leak down in the manifold causing hard starting. Yes they do get saturated with gas and lower.
Just a thought, Im no expert
Beef

Ayuh,........ My thought, Exactly.......

Having to hold the throttle Wide Open tells Me it's Flooded........


Btw,.....
Beef,........ I found My Whistles,.... I'll be installing at least 1 of them this weekend............

 

[etbill52]

Re: 5.0 V8 does not start easily when it is warm

I'd check if the choke is openning fully when engine is warm. If you smell the oder of gas after shutdown, the carb is probably leaking into intake causeing a very rich/flooded condition, that requires the throttle to be opened fully, to clear.

Had the same problem last weekend, took the grandkids out, the motor started easy when cold, (Inline 6 mercruiser) after we run it for 1/2 hour stopped to talk with someone and it would not start back, I checked the choke and it was closed tight as hot as the motor was. I adj. the choke back to where it opening up and it started easy the rest of the day.

 

[fsamie1]

Re: 5.0 V8 does not start easily when it is warm

Thanks guys, Took it out yesterday with new 140 thermostat. During cruising, temperture was the same as before about 170. same problem.
Choke is wide open when it is warm and I do not see any gas leaking from jets.
Came back and checked spark timing. It was running at TDC. Made adjustment to 8 deg before TDC. Would this cause it to run hotter? Where is the idle mixture adjustment screw?

 

[John_S]

Re: 5.0 V8 does not start easily when it is warm

That was probably your starting problem.

What carb do you have? BTW, are we talking Merc, Volvo, or OMC? You want to set the timing correctly, idle mixture, and idle speed.

170 with a 160 thermostat is normal. Why it didn't drop with the 140, don't know, maybe the timing. Make the adjustment and test.

PS: If it was timed in spring and hold down clamp was tight, something might be wearing in your distributer.

PSS: That much of a timing change you should also see a increase in engine power.

 

[a70eliminator]

Re: 5.0 V8 does not start easily when it is warm

Wow 8* retarted, I'll bet your carbs idle was set way up there out of the transfer slots, I'll bet you had to drop it back once your timing was correctly advanced.

 

[fsamie1]

Re: 5.0 V8 does not start easily when it is warm

Thanks guys, starts pretty fast in about 1-2 seconds after I set the timing to 8 BTDC.