Idle affected by fuel leak?

[rebars1]

1971 merc 888, Ford 302, 188hp. My engine does not idle below about 700rpm without dieing and does not want to restart without pumping the thottle once or twice. I've drained and refilled the tanks and replaced the fuel filter. I had the carb (Holly 2 brl) rebult last year, but I've noticed a little fuel leaking from under what I think is the accelerator pump. Could this affect the idle? I would think the rebuilders would have replaced the rubber diaphragm in there, but maybe they didn't. Time for another rebuild?

 

[waterone1@aol.com]

Re: Idle affected by fuel leak?

When you say "under the accelerator pump" do you mean under the lever that pushes down on the shaft ? As in fuel leaking out around where the shaft sticks up through the carb ?

 

[rebars1]

Re: Idle affected by fuel leak?

waterone1: Yes. That is the location. Excellant description.

 

[waterone1@aol.com]

Re: Idle affected by fuel leak?

Most of the carbs I've worked on have been Rodchesters....not too familiar with the holley. I have to say that anytime I hear of any type of fuel leak in a boat...get it fixed. As for your idle question, did this problem just start, or has it been doing it ever since you had the carb rebuilt ? Or were you trying to fix this problem by having the carb rebuilt ? Is the choke closing when the engine is cold ? Is the carb tight on the intake manifold ? It has happened more than once that someone sends off a carb to be rebuilt, puts it back on with a new gasket and after a few weeks of engine heat and bolt torque, the gasket "crushes" a bit and the carb needs to be re-torqued to stop a vacume leak.

 

[rebars1]

Re: Idle affected by fuel leak?

I've been restoring this boat for about a year and had the carb rebuilt last Sept. However,I had only run it muffs a couple of time before pulling the engine to replace the Y pipes. The idle was not completely resolved prior to pulling the engine. Now that the engine and outdrive are back in, I'm trying to work on the idle. I think the leak was there even after the rebuild.

 

[Mahoney]

Re: Idle affected by fuel leak?

I had the EXCACT same problems with my 1978 22 GM v8 rochester 4 brl, rebuild carb, and didnt help much. The big help was replacing the points and better yet just scrapping it and getting an electronic ignition conversion kit.<br /><br />Immediat improvement. With the points I noticed even when I adjusted the dwell correctly, rechecking it again after running it on the muffs a couple times, the gap had changed slightly.<br /><br />I highly recomend, depending on the age, new plugs, wires and electronic ignition. You should notice a huge difference.<br /><br />Also make sure the fuel is not soured.

 

[trog100]

Re: Idle affected by fuel leak?

yes.. i recon the problem is best solved by looking somewhere else other than the carb.. 700rpm is quite low.. not quite low enough but not far off.. getting a nice low and reliable idle does need most things to be about right..<br /><br />fitting elctronic ignition did improve my idle reliablity.. not by a massive amount but anything helps..<br /><br />trog100

 

[Silvertip]

Re: Idle affected by fuel leak?

Mahoney - the reason the gap changed (which obviously affects dwell) is because the bushings in the distributor were probably worn which allows the shaft to move or wobble. Unless that shaft stops in exactly the same spot every time you probably would experience point gap/dwell change (but only because it was being measured on a wobbly shaft and it really wasn't changing). I have also seen point sets where the fixed contact was not set in the bracket tightly which causes bounce. These are the kinds of problems that drive a tech to drink (if he/she is not there already!)

 

[rebars1]

Re: Idle affected by fuel leak?

I'll check the bolt torques. The bottom gasket look wet, but it might be from the accelerator pump leak.