5.7 Merc stalling at idle speed

[dhillis]

I am new here and this is my first post. I just bought a 1982 Regal Regency 21FF. The boat is in good condition for its age.<br /><br />It has a 5.7 Chevy motor and I believe Merc pre alpha stern drive. The motor was just recently serviced for the season by the previous owner's marina. Everything on the motor looks good and the carb appears to be rather clean.<br /><br />I have had it on the water approximately 7 times now. During the last two trips while entering the river I would back the throttle down to idle (800-900 RPMs) in the "no wake zone". It would idle fine for a minute or two and then the motor would quit. It has done this four times now in the river and when it happens the motor kind of hiccups and then quits. I can then start the motor back up immediately and it will cruise at idle speed without a hitch, then all of a sudden it hiccups again and quits. I have found that holding down the throttle lever at approximately 800-900 RPMs helps.<br /><br />I should note that the previous owner had approximately 30-40 gallons in the tank and I have since added approximately 70gals since I've owned the boat. I don't believe it is bad fuel since it runs very good under all circumstances but idle speed. <br /><br />I appreciate any feedback.<br /><br />Thanks,<br />Dan

 

[bamadave]

Re: 5.7 Merc stalling at idle speed

welcome to the forum. Is the flame arrester clean? Start by replacing the fuel filters. Also,try spraying carb and choke cleaner in the carb throat while the engine is running? Spray the cleaner until the engine starts to die and stop until the engine picks back up. If all this fails, have the carb rebuilt. Good luck

 

[boathog]

Re: 5.7 Merc stalling at idle speed

you can also try opening the low speed adj. half a turn on the carb

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

bamadave, I actually cleaned the flame arrestor just prior to leaving for the water, so it was completely cleaned out. How many fuel filters are there and where may I locate them? This boat did not come with any manuals or such... <br /><br />Boathog, can you direct me to where the low speed adjustment is on the carb? <br /><br />Thanks a lot,<br />Dan

 

[Reel Poor]

Re: 5.7 Merc stalling at idle speed

Can you identify the carb for us?<br /><br />Two Barrell ?<br />Four Barrell ?<br /><br />Dualjet ?<br />Durajet ?<br />Quadrajet ?<br />Holly ?<br />Edlebrock ?<br />Other ?

 

[sker crunch]

Re: 5.7 Merc stalling at idle speed

I have the 5.7 and pre alpha setup same as you on an 82 viking. You have a fuel water seperator which looks like an oil filter on the front lower left of the motor as you stand in front of it and a small filter inside the carb where the fuel line threads on to it. I have a Rochester 4bbl and mine is a small plastic tube covered with very fine screen.

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

It is a four barrel, but I am unsure of what brand it is. Is there anyway to identify that?<br /><br />Thanks,<br />Dan

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

Thanks sker crunch, I will check those filters tomorrow when I have some time.<br /><br />Dan

 

[sker crunch]

Re: 5.7 Merc stalling at idle speed

Mine says Rochester Quadrajet on the side of the carb.

 

[Reel Poor]

Re: 5.7 Merc stalling at idle speed

Does it look like this one? If so it's a Rodchester Quadrajet.<br /><br />

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

Thanks for the picture, I will check on that tomorrow when I have some time.<br /><br />Dan

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

OK guys, it is a Rochester Quadrajet.

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

Upon further inspection, I pulled the fuel line off the carb and found that the inline filter (Fram) was in pretty rough shape to say the least. Let's just say I was able to pull "rust" type debri from it. I also checked the spin-on filter/water seperator and it looks brand spankin' new. <br /><br />A couple of other things I noticed... <br /><br />1) On the starboard side of the motor, near what I assume is the choke, there was a wire with a connector on it, but it wasn't attached to anything. I could not locate another wire that could possibly be connected to it. <br /><br />2) I found a ground wire disconnected. The wire runs from what I think is the inside outboard drive mounting plate to what looks like the throttle control plate at the rear of the motor. I reconnected that, but couldn't tell you what it relates to.<br /><br />Any more suggestions or opinions appreciated.<br /><br />Dan

 

[Reel Poor]

Re: 5.7 Merc stalling at idle speed

Has it been tuned up? Plugs, wires, cap, rotor, new fuel filters, timing checked and set if needed.

 

[bruceb58]

Re: 5.7 Merc stalling at idle speed

Quadrajets are good idling carbs. Much better than Webers in my opinion. Always liked them better on boats that I have used for trolling.<br /><br />However, no carb will idle well if the carb is not set up well or is gummed up or if the fuel quality is in question. <br /><br />Is your choke all the way open when the engine is warmed up?<br /><br />It might be worthwhile seeing how many turns the idle mixture screws are. They should both be out the exact number of turns. If they aren't, it means someone has been adjusting the carb improperly.<br /><br />Assuming everything else on your engine is ok including plugs, wires, points, rotor, cap, dwell and timing adjustments, your carb may just may need to be rebuilt.

 

[dhillis]

Re: 5.7 Merc stalling at idle speed

The boat was completely tuned up before the boat was put in the water. This was done by the previous owner's marina shop this spring. I will check a few things today while on the water, because yesterday was awful and didn't get a chance to go out. I am having trouble finding that little fuel filter that is mounted inside the fuel line just off the front of the carb. It seems that no marina stores here even carry them. <br /><br />Anyway, I am going to get on the water today and will report back if I have any problems.<br /><br />Thanks,<br />Dan

 

[John_S]

Re: 5.7 Merc stalling at idle speed

dhillis, engine tune-ups can mean just about anything. It is nice to know exactly what the particular marina does for "their" tune-up. Between winterizing and spring engine tune-up for me, it means, distributer cap, rotor, plugs, timing, carb idle, mixture, & choke, clean arrestor, oil & filter, water seperator, lubrication of shift and throttle links, and probably a few things I forgot off the top of my head. <br /><br /> Your idle problem does sound like you are running too rich, and plugs are loading up. Restart and quick rev, and it cleans them off. The easy checks have been mentioned, choke all the way open, and adjustment of mixture screws. Recommend getting the Merc manuals for your engine and outdrive. They are superior to aftermarket manuals.