Hard Starting After Warm.....Otherwise Runs Perfect

[UNCC Grad]

We ran into an issue today at the lake with my 84 Skier not wanting to start after sitting. It started normally with 2/3 tank of fresh fuel when we left the ramp and ran great. We stopped and swam for a few minutes and it started back fine and we pulled a few people on the wakeboard and it was still running great. Later on we shut down again to change riders and it didn't want to start back up. We finally got it going again and headed back to the ramp, no sputtering, hesitation, etc.

Fast forward to tonight and I am looking at everything that I can think of. I hook up the fake a lake and it starts fine. Run it for a while and shut it down for a few minutes and it doesn't want to start back up. I try to drain the fuel/water seperator and nothing comes out which was odd so I pull the fuel line and it's bone dry. I blow compressed air into the line to make sure it's not clogged and I can hear the air gettting into the fuel tank so that seems OK.

Could it be my mechanical fuel pump going out? Seems like if that was the case it would have higher rpm issues.

Is there another fuel pump in the fuel tank that could be going bad? For some reason fuel is not getting from the tank to the fuel pump/carb. I guess I was under the assumption that the mechanical fuel pump pulled the fuel from the tank under a vaccuum.

[rodman]

We ran into an issue today at the lake with my 84 Skier not wanting to start after sitting. It started normally with 2/3 tank of fresh fuel when we left the ramp and ran great. We stopped and swam for a few minutes and it started back fine and we pulled a few people on the wakeboard and it was still running great. Later on we shut down again to change riders and it didn't want to start back up. We finally got it going again and headed back to the ramp, no sputtering, hesitation, etc.

Fast forward to tonight and I am looking at everything that I can think of. I hook up the fake a lake and it starts fine. Run it for a while and shut it down for a few minutes and it doesn't want to start back up. I try to drain the fuel/water seperator and nothing comes out which was odd so I pull the fuel line and it's bone dry. I blow compressed air into the line to make sure it's not clogged and I can hear the air gettting into the fuel tank so that seems OK.

Could it be my mechanical fuel pump going out? Seems like if that was the case it would have higher rpm issues.

Is there another fuel pump in the fuel tank that could be going bad? For some reason fuel is not getting from the tank to the fuel pump/carb. I guess I was under the assumption that the mechanical fuel pump pulled the fuel from the tank under a vaccuum.

Does it start when the engine is cold or cooled down? Are you getting gas when it does not start. Is the motor spinning fast or slow?

If you have gas when it does not start it isn't a fuel pump. If it dosn't want to start when it is hot try backing the timing off a touch.

[Devin Perry]

I had a similar problem with mine does it act like it is flodded after it sits? mine was a bad fuel pump over presurizing and pushing past the needle and seat boat would run fine then i would stop to let someone in the boat go to start, no start, go full throttle then chug back to life and run good.

[Woodski]

Good chance you are suffering from vapor lock. You might try insulating the fuel lines. When it happens, a cold rag on the fuel pump and lines should reduce the boiling fuel and get you started sooner. You didn't accidentely get E85 or use a high alcohol content fuel by chance?

[UNCC Grad]

I can't really say if it starts better cool or not b/c there was a storm we were trying to beat yesterday so I never had time to let it cool. It also acts as if it is starving for fuel, not flooded when this happens.

Today I tried to disconnect the fuel line at the carb and measure the amount of fuel while cranking. 10 seconds cranking resulted in about 6 oz of fuel. I tried this with and without the fuel fill open, incase there was a pressure issue going on and both ways got the same amount of fuel. Talking to Ski DIM, they say I should be getting around 16-20 oz of fuel after 10 seconds of cranking, maing me think my fuel pump is bad. I didnt have a fuel pressure guage at the time to see what the reading was to the carb.

I picked up a new fuel pump today and hope to install this evening and try it out with the fake a lake, if it doesn't storm. Everything is pointing towards vapor lock except that I cannot understand why the line from the fuel tank and the fuel/water sep were dry. My only thought is that the fuel pump is going out and doesn't provide enough vacuum at cranking to keep the system primed.

If anything, the new fuel pump will rule out one possibility. It looked like it was the original and was probably due for replacement anyway.

[JasonK]

I had a problem a few years ago. I tried a few things incl. new pump, and I eventually bypassed my water-seperating fuel filter and the problem went away. This year I re-introduced the w-s filter with a new filter an the problem did not return.

Buy a double ended barb and bypass the filter housing, just to be sure. Good luck.

[kengrutza]

I'm gonna go a completely different direction.

I am thinking the heat shield in the starter. This is very common on cars of the same vintage.

When the engine gets hot the heat shield is supposed to protect the windings in the starter to help it work properly. As they age, this breaks down allowing the current to pass from one coil to the other in the starter effectively shorting it out.

Have you looked into this?

Ken

[hypo]

I'm gonna go a completely different direction.

I am thinking the heat shield in the starter. This is very common on cars of the same vintage.

When the engine gets hot the heat shield is supposed to protect the windings in the starter to help it work properly. As they age, this breaks down allowing the current to pass from one coil to the other in the starter effectively shorting it out.

Have you looked into this?

Ken

sounds like a ignition problem,or timing may be off