1976 I6 1500 fuel pump issue?

[rriddle99]

Hi all again. Thanks everyone for helping me out before. I'm using the boat almost daily with very little issue. Here is one more I need help with:

Most of the time I run slow through no wake zone for a period of time (about 1200rpm or so for 3-5 minutes or more) when I get through it and go to take off the engine bogs and dies. I can start it up and then most of the time it will go. One thing I noticed today is it seems to do ok if at the end of the no wake area if I pump the bulb it will take off pretty good. That's telling me that I may not be creating enough vacuum to operate the fuel pump correctly. Anyone feel differently about that? Is there a known issue with this? What about an electric fuel pump? I know these needles seat at low pressures but wondered if anyone was successful at converting this without running an overflow line back to the tank.

Thanks all for any insights you can offer!

 

[Dave1027]

Re: 1976 I6 1500 fuel pump issue?

Rebuild fuel pump. Check fuel lines and primer bulb.

 

[rriddle99]

Re: 1976 I6 1500 fuel pump issue?

Fuel pump has been rebuilt
Lines and bulb are new as well

 

[Chris1956]

Re: 1976 I6 1500 fuel pump issue?

The pulse lines need to be air tight, where they connect to the block and pump. Make sure they are not kinked. I always had trouble with them, so I would use some sealer on the brass nipples, and route them so they wouldn't kink.

 

[Chris1956]

Re: 1976 I6 1500 fuel pump issue?

Also look for air leak in fuel lines and fuel tank fittings.

 

[rriddle99]

Re: 1976 I6 1500 fuel pump issue?

Thank you Chris. Is there a length spec on the pulse lines? Or a not to exceed length?

 

[Chris1956]

Re: 1976 I6 1500 fuel pump issue?

There probably is, but I do not know what it is. Make them long enough not to kink, and you should be fine. Air leaks at the fuel line connections are probably more likely your issue.

 

[rriddle99]

Re: 1976 I6 1500 fuel pump issue?

I replaced the incoming fuel line that connects to the inlet on the fuel pump, both pulse lines (the lower one was soft and felt like it would collapse easily under vacuum), and cut the end off the outlet fuel line and reconnected it to the fuel pump as it showed signs of cracking but only on the end. Put it on the water and there was actually a noticeable difference on low end and less sputtering during hole shots after long no wake situations. I'll work on the fuel line feeds from the tank soon too I was not able to reach them easily and have to remove equipment from the boat to do so but there was enough change that I'm going to be able to tune the carbs a little better as well.

Thank you Chris :joyous:... I'll post once I get the rest complete and see if that changes the operation as well.