Rebuild or just clean ?

[nthrnNYker]

I just bought a '83 Bowrider Capri in pretty nice shape, along with an 85 hp Chrysler Force engine...a hellova deal on both.

When I got the boat, it had a full tank of gas, but it just didn't have the strong smell of gas, so I replaced the gas in the tank, then drained the bowls on all three carbs....water in the bowls in all three. I replace the bulb and the quick-release tank connector...as both were leaking pretty good and sucking air.

I got it to idle after a bit at home, and it would rev up pretty good as well...so I took it out on the lake for a test run.

Once out on the lake, the motor would stall at idle unless I periodically hit the electric choke on the ignition switch. The friend I was with, who had a bit more experience than I with outboard motors, temporarily bypassed the neutral safety switch so that the motor would start in gear. Once he did that, it would still stall after a very short period of time, but he tried to immediately open up the throttle while in gear. OMG, did that engine take off. That thing just FLEW with nary a hiccup. We went up the lake about six miles and back and that engine PURRED the whole way !

However, as we neared the boat launch, we dropped the speed of the engine. At just under 1/2 of WOT, the motor started to seriously sputter and cough, and as we decreased the rpm of the engine even more, the engine died. It would start up again, but unless we choked it periodically with the ignition switch, it would immediately die.

Now, my friend says it sounded like the low-speed jet was obstructed, and just needed cleaning and/or blown out with compressed air.... but I would hate to take the whole contraption apart just to clean it, put it all back together and not fix the idle issue.

Would it be better to rebuild the carbs while I have them apart ?

(please keep in mind I am not a mechanic and tend to have leftover parts when I am done )

 

[pnwboat]

Re: Rebuild or just clean ?

If you are going to work on the motor yourself, the first thing you need to invest in is a service manual. Either one by Clymer or original Force manual. These are available on-line via E-Bay, Craigslist etc. I wouldn't recomend the manuals by SELOC. Not laid out well and confusing.

These Force carbs do not have a "low speed jet". They do however have idle circuit passages in the carbs. The carbs themselves are pretty simple. They are not very forgiving as far as adjustments etc. If you're going to take the carbs apart, you should get a rebuild kit. If you're not mechanically inclined, and you want to tackle this yourself, you should have a mechanically inclined friend looking over your shoulder. Worse case scenario, you could ruin the engine by running it with too lean a mixture, or the engine may run worse after you re-build the carbs.

 

[nthrnNYker]

Re: Rebuild or just clean ?

Well, it I got the carbs off the motor & taken apart. It looks like I will need a gasket set at the least for each of the three carburetors.

The top carb had no gas at all in the bowl, and it looks like the bowl gasket was mis-aligned before and mashed the gasket into a shape it wasn't designed to have. The other two carbs each had the bowls full of gas.

Now each of the carbs looked clean as a whistle, except the lowest carb. That one seemed to be plugged by rust as shown here :





(just click on the above photos for close-up view)

Is it possible that just that single plugged orifice could have been the source of my idle issues with this motor ? Just the one carb out of the three ?

Beyond that, can anyone recommend a good source for gasket/rebuild kits for this engine ?

 

[john from md]

Re: Rebuild or just clean ?

If the engine will not run at low speed, is the bulb soft when it shuts off? If so, the problem is the three check valves in the fuel pump. The alcohol in the fuel is causing the older check valves to stick. If you can get it up to high rpm, the fuel pressure is enough to overcome the sticking.

These valves cost $5 each and can be obtained from www.mercruiserparts.com, www.boats.net or www.crowleymarine.com

The plugged orifice is the main jet on the carb. That will affect operation at throttle settings above 1/3rd advanced. It will not affect idle as it has a separate circuit.

Regards,

John

 

[nthrnNYker]

Re: Rebuild or just clean ?

Uh oh...pulled a big miscalculation here. After reviewing some of the posts on these forums, the fuel/oil mixture calculations I made differed radically than those made on here (not to mention I just threw the two cycle oil I use for my chainsaw in the gas).

I noticed that most of the posts on here specified 16 oz of two-cycle oil to 6 gallons of gasoline. For some reason, I had it in my mind that 1 gal=64 oz, therefore 6 gallons= 384 oz, and 384/50=7.68 oz of two-cycle oil. And that's pretty much what I threw in the gas.

Well, thank god the motor is no worse for wear for the experience as far as I can tell. However, and just for curioisity's sake...might the miscalculation in the oil mixture been a contributing factor in the motor's idle issues ?

Not that it much matters, as I've followed John & pnwboat's advice and ordered the carb rebuild kits along with most of the parts for the fuel pump to rebuild both from boat.net. (wow....I can tell I'll be ordering endlessly from THAT place ! )

 

[john from md]

Re: Rebuild or just clean ?

The lack of oil would definitely have caused some of the problems you saw on your first run. Hopefully, you did not score the cylinders too badly and you will be able to get by. At least it didn't lock up on you.

Repeat after me, 50 to 1, 50 to 1, 50 to 1.

John

 

[nthrnNYker]

Re: Rebuild or just clean ?

DARN DARN DARN !


Turns out that replacement check valves for the fuel pump are on "National Back Order" (possibly due to the strike at the Mercruiser plant in Wisconsin).

(and yes, even after rebuilding the carbs, the engine will not idle correctly and the pump bulb does not stay hard)

Now my question is....is this the end of the boating season for me, or can a bit of carb cleaner provide a temporary fix and free up the check valves --- along with a replacement of the diaphram, screen, and gaskets (the parts they DID have) ?

 

[john from md]

Re: Rebuild or just clean ?

Pull the fuel pump off and remove the valve held in with screws. Using a toothpick or somthing similar, push it gently and see if it sticks. Do this several times. Also, check the other pressed in valve that shows the poppet side of the valve. If they are sticking, it is because they have swelled due to the alcohol in the fuel. Usuall, the valves suseptable to swelling are either clear or tinted orange. The new valves are grey or black.

John

 

[nthrnNYker]

Re: Rebuild or just clean ?

EUREKA !

On the off chance that I might get lucky at least ONCE in this fiasco, I called up Crowley Marine to see if THEY might have the check valves. SUCCESS ! They had 8 on hand, and I had them next-day air 3 of them. The boating season is not yet lost !

John-- on your advice, I removed and disassembled the fuel pump. Sure enough, the check valves were the old ones, clear in color. And also sure enough, the check valve in the center seemed to be frozen in place when checked with a toothpick. However, when I checked for proper operation by first sucking, then blowing into the hose that leads from the pump to the carburetors, the valves seemed to function correctly (other than the annoying 'honking' noise they made).

Be that as it may, the new ones will be arriving on Monday. Now, my question is...does it make a difference exactly how the old pressed-in valves are removed (ie, prying them out with a long thin screwdriver) ? Further, is a special tool required to press in the new ones ?

 

[john from md]

Re: Rebuild or just clean ?

Glad to see you got lucky.

When the valves are sticking, it doesn't take much to stop them from working. You are only looking at about 2 LB of suction and maybe 5 lb pressure at WOT from the diaphram type pump.

Two valves are easy. One is mounted with screws. When replacing this one, remember to use a gasket with it. The next can be drifted out with a drift pin through the hole in the casting. Spray liberally with some sort of penetrating oil prior to drifting out. The last is in a blind hole. You need to make a pulling tool to pull it out. I used a dremel tool to cut partially from the inner to the outer which lessoned the pull in the blind hole. Don't forget to use oil on this one also.

To install, first blow all chips away and make sure the cavities are dressed out if you gauged them a little. Lightly lube the outside of the valve with engine oil and then either press in or drift in with a hammer using a socket seated on the rim of the valves. MAKE SURE YOU INSTALL THEM IN THE RIGHT DIRECTION. Insure that you seat them all the way into the cavity. Also, don't damage the metal frame that houses the valve poppet or all this work will have been for nothing.

Measure twice, cut once really applies here if you know what I mean.

John

 

[nthrnNYker]

Re: Rebuild or just clean ?

John-- Another question for you....

The guy I had tinker with the engine to get her up and running expressed a preference against those 'surface gap' plugs, and he had me replace with regular champion equivalents. Was this a bad move ?

Second, after that single trip out on the new plugs, I removed and examined them. The plugs from the top and middle cylinders seemed pretty clean. The plug from the lower cylinder looked pretty fouled, and it shouldn't be, with the fuel/oil mixture error I had.

Would that clogged main jet been the cause for the fouling of the lower plug ?

 

[nthrnNYker]

Re: Rebuild or just clean ?

Yet another question, John.

The old plugs that I pulled were the NGK BUHX, which crosses over to the Champion L76V.

However, doing some research, I am under the impression that the correct spark plug for this engine is the Champion UL18V.

Which is the correct plug ? And does it make a difference ? Heat range, ect ?

 

[john from md]

Re: Rebuild or just clean ?

You must use surface gap plugs or you will burn a hole in the piston. The engine will not idle as well with them but this engine was designed for WOT all the time. If you use L gap plugs, you will burn a hole in your piston.

You can run UL18V or BUHX. You can also try the BUHW which is the same as the BUHX without the internal gap that the spark has to jump. Sometimes in older engines, the BUHW works better.

A clogged jet will not cause fouling as no fuel is gettng through it. Sticking check valves will cause the engine to lean from the top down and that might be the reason for your clean upper plugs and dirty number three plug. The engine shut off before the third carb went lean.

John

 

[wsroufe]

Re: Rebuild or just clean ?

I recently bought a 90 hp Chrysler outboard and it basically does the same thing. What is the best manual for this procedure? Does anyone have PICS they can post? This is my first venture into motor boats and my family is loving it so far. John you really seem to know your way around these Chrysler engines. Is this three valve total or per carb?

 

[john from md]

Re: Rebuild or just clean ?

wsroufe,

Please read the sticky on how to get the best response from your question and then start a new thread.

Thanks,

John

 

[wsroufe]

Re: Rebuild or just clean ?

Thanks. I didn't mean to hijack the thread. I will start a new one.

 

[nthrnNYker]

Re: Rebuild or just clean ?

A clogged jet will not cause fouling as no fuel is gettng through it. Sticking check valves will cause the engine to lean from the top down and that might be the reason for your clean upper plugs and dirty number three plug. The engine shut off before the third carb went lean.

John

ARRRGGG ! After much trouble getting that third pressed-in check valve removed, and the new diaphrams, gaskets & check-valves installed, and the proper spark-plugs re-installed.....STILL won't start !


Then I checked the plugs for spark.....DA** ! No spark from the bottom-most plug....NOW what.

Well, after careful examination, discovered that I had a wire caught and flattened under one of the bolts that hold the fuel pump in place on the block. How the HECK did that get there ? After removing the wire, gave it another go .... SPARK ! :redface:


Well, now there seems to be water throughout the fuel system, and I have no idea how. Brand new tank of gas, filled to the brim (no chance for condensation there), the entire boat was covered all this past two weeks, and I had all three carbs out and cleaned....how the HECK did water get in the system ? ? ?

Well, tomorrows another day....let's hope it goes better than today did !


(Oh, and by the way, John...thank you much for all your assistance....it has been invaluable)

 

[nthrnNYker]

Re: Rebuild or just clean ?

Ahhhhh, darn, darn, darn.....

Finally got all the water cleaned out of the carbs, the lines, brand new plugs, and a fresh (and clean) tank of gas.

Still won't idle....will start with choke, but not idle. Also, when choked, the fuel will drip heavily out the mouth of the carbs....is this normal ? And even when started, the engine can be rev'ed by means of the throttle linkage, but almost immediately dies...if anything, it is running worse than prior to the fuel pump rebuild.

The fuel pump is delivering gas, and plenty of it....when pump hose is disconnected and engine cranked over. Plugs are getting plenty of spark on all three cylinders. What else might the problem be ?

The only issues that might remain, I believe... is either the motor needs to be timed, or the idle mixture screws are mis-adjusted. Might the previous owner adjusted the carbs in order to compensate for the sticking check valves ? Would this be something one would normally do ?

And finally...if I should check for the proper idle mixture adjustment....what should the proper settings be ? I note than on some of the posts on this forum specify 7/8ths out, some 1 1/8 turns out...Which is the correct settings ?

 

[john from md]

Re: Rebuild or just clean ?

As simple as idle settings should be, they are not on mechanically timed engines.

Start with the basics. Fuel mixture screws 1 turn out, carb linkage adjusted so that the throttle cam contacts the throttle roller at idle in neutral.


Pump bulb until firm.

Set throttle to fast idle.

Push in key to choke and turn to start.

However, if the timing is not correct, then someone may have adjusted the idle rpm screw to compensate. When this is done, the trottle plate moves to open and the engine draws fuel from the idle and mid range circuits. When ever you have idle problems it is advisable to check your timing and make sure it is correct.

As to fuel spitting out of the carb, this can happen with choking and the cylinder is getting to much gas.

John

 

[further]

Re: Rebuild or just clean ?

I had a similar issue with hard or no start and found that the carb linkage was improperly set and throttle plates remained open allowing too much fuel to get through during starting. Also, at one point I had fuel spitting out the carbs and it ended up that I had the floats improperly set. Hope this helps some. Good luck