1978 70hp Hot Start Problems

[tlynch99]

Hello,

I have a 1978 Evinrude 70hp, we were out on the lake on Saturday cruising around for a few hours. The problem I am having is when I turn the engine off, and let it sit for approximately 10 - 60. The engine starts easily after sitting, but when I engage the forward drive and go to throttle up the engine boggs and then stalls. I was able to get the motor up and running by starting the engine lifting the warm up level up all the way (motor would idle around 1200). I would run the engine at 1200 rpm for a few minutes, then the engine would throttle up.

What is strange is that when the engine has been running for a while, I can throttle down to idle and then back up to WOT without problems, it's only when the engine has been off, once started it won't throttle up.

I am suspicious of the carberators, the probably need a cleaning, but I wanted to ask if any one else has experienced these symptoms.

Thanks
TJ

 

[tashasdaddy]

Re: 1978 70hp Hot Start Problems

i agree 100%, sounds like the float needle is not closing all the way. when sitting, pressure is forcing fuel into the intake, flooding the motor, and you have to rev it to clear the excess fuel.

http://forums.iboats.com/showthread.php?t=244013

 

[tlynch99]

Re: 1978 70hp Hot Start Problems

If I rebuild the carbs would that fix the problem? Should I order the kit with the new float? It definitely makes sense about the pressure forcing gas into the carbs.

TJ

 

[tashasdaddy]

Re: 1978 70hp Hot Start Problems

it should. there is never a guarantee. but it is the first place to start.

 

[guy74]

Re: 1978 70hp Hot Start Problems

Try repriming the fuel system with the primer bulb. Might be a marginal fuel pump that loses prime and won't reprime at idle. You may be running the fuel out of the carbs before the fuel pump catches up. Just a thought, might help diagnosing the problem.

 

[tlynch99]

Re: 1978 70hp Hot Start Problems

I did try pumping the priming bulb, the engine was running at idle not in gear, pumping the bulb didn't seem to help at all. It wasn't particularly running rough or anything, just when I put it into gear it stumbles and then dies. I also tried pumping the bulb before starting didn't seem to help.

 

[guy74]

Re: 1978 70hp Hot Start Problems

If that didn't help, then TD is probably right, it's flooding. I'd say you are on the right track with a complete rebuild on the carbs. Goodluck