OMC with new carb ... throttle adjustment help?

[wahzoo]

I have a 1989/1990 vintage OMC outdrive .. new carb but place out of business and didn't tune throttle travel correctly. I have the OMC side mount control (concealed version) with only the handle and trim control on it visible. I have trouble starting without starter fluid, and it appears to me the throttle cable needs another 1/4" or so movement to be fully open and to allow me to initially pump lever for some fuel to squirt into carb. High end speed also gone which also matches. When I opened control box I don't see anyway to adjust the throttle distance (idle is fine) and on the carb side I se one black plastic cover over end which looks like it might adjust but that would seem to only move the throttle more advanced .. I like idle where it is. And finally when I hand push the throttle on the carb it opens the butterfly valves to fully open with that 1/4 distance ... otherwise appears the second two barrels stay closed. Any help appreciated ... will try and upload some pics.

https://www.amazon.com/photos/share...BS2oJ0ajlPOeAN/gallery/8IcsXieASrmoimhwy3un4A

 

[alldodge]

I have trouble starting without starter fluid, and it appears to me the throttle cable needs another 1/4" or so movement to be fully open and to allow me to initially pump lever for some fuel to squirt into carb

You have a fuel issue, so need to fix that before I would worry about the extra 1/4 inch. My guess is the last 1/4 inch of rotation will have no effect on top end. The carb can flow more aire then the motor can take in, so get the fuel issue fixed first.

Check fuel pressure my guess is its low. Rebuild the carb and fix the accelerator pump

 

[Lou C]

Looked at your pix, also agree with post above in that you should not need starting fluid to start it.
What you have is an Edelbrock style carb which was not the OE fitment on these engines (they came with Quadrajets). You probably need to adjust the trunnion which is the part that is held in that clamshell clamp bolted to the intake manifold. I would:
disconnect the throttle cable at the carb. pop open the choke open the throttle all the way with the lever on the carb. See if the primary (front) throttle blade opens all the way. If so then throttle issue is due to the conversion not being properly adjusted. The way you adjust an OMC throttle trunnion:
disconnect the cable at the carb, then set idle speed.
Next,reconnect your throttle cable to the carb and have someone who can spin the prop for you ENGINE OFF so you can shift the remote control into fwd gear. Now loosen the bolt that holds the 2 halves of the clamp for the trunnion so you can turn it (round fitting on throttle cable). Then take the remote control and shift half way back to Neutral. Now adjust the trunnion so that it pulls tight on the cable, closing the throttle. Then re-tighten the bolt holding the halves of the trunnion clamp together.

Then test it to make sure the throttle opens all the way (ENGINE OFF) and with it running make sure the engine reliably returns to idle speed.

 

[Bondo]

Check fuel pressure my guess is its low. Rebuild the carb and fix the accelerator pump

Ayuh,..... Welcome Aboard,..... I agree, ya got a fuel delivery issue,......
That carb is vacuum 2ndaries, that last bit of throttle ain't the problem,.....

Have ya inspected the Contents of the fuel filter for anything but clean fresh gasoline,..??

 

[Scott Danforth]

please explain in detail exactly how you try to start the motor. exactly

also, as soon as your throttle shaft is moving, you should have fuel squirting, if you dont, your accelerator pump circuit needs attention.

 

[wahzoo]

All excellent things to look at. I normally would start the engine (in the past) by putting the control into the fast idle and pump it a few times which traditionally squirts some fuel in the carb ... then back to idle or leave in fast idle if cold and hit starter switch.

Now I have to squirt starter fluid into carb, then it starts in fast idle setting on controller, and runs consistently until I turn off engine. However if I turn the engine off even after warmed up, it appears to need the starter fluid again. Guess that indicates some initial fuel pump issue or something else like the carbs work differently and different pump?

My thought was that on old carb it was that full throttle pumping (fast idle with handle pulled out) that put the initial fuel in, but now after pumping throttle I can sniff in carb and smell nothing.

Also interested in checking the fuel filter (have to find it) as guess it could be such that initially blocking but after engine running and full vacuum it sucks the gas regardless?

Thanks to all again! and for any additional insight.

 

[Bondo]

Also interested in checking the fuel filter (have to find it) as guess it could be such that initially blocking but after engine running and full vacuum it sucks the gas regardless?

Naw,..... Yer lookin' for Evidence,..... Crap or water in the filter's Contents,.....

If the filter is fulla crap, so is the tank, 'n no doubt some of it is now in the carb, pluggin' the idle circuit, or other passages,.....,.....