RPM Slow when 'In Gear'

[Persistence]

My A4 runs fine in neutral (ie- responds to throttle the way you'd expect) however, when I drop it into gear (either fwd or rev) the rpm drops to idle and stays there no matter what you do with the throttle handle or the control arm at the carburetor. I've check the packing box and it seems to be adjusted correctly with a drip every so often. Someone suggested it wasn't a drive train problem but an engine problem, either timing or carb. I changed the plugs (sure enough the old ones were carboned up and I just put them in in July) but the new plugs didn't seem to make any difference. I put some vice grips (using a cloth) on the drive shaft between the engine and the stuffing box and when in neutral it takes about 4 ft lbs of effort to turn the shaft. I've pulled the boat (as you see in the avatar) and am ready to fix the problem - any suggestions?

Dave
1976 Catalina 30 Hull #488

[edwardc]

Carbon fouled plugs suggest either you'rt running too rich, or you have exessive back pressure, due to an exhaust blockage. Back pressure would also explain the inability to generate any power under load. The engine just can't breath because it can't exhale. In neutral its fine, but in gear all it can manage is idle.

Check your exhaust, particularly at the water injection point. This is usually where it cruds up, especially if you're in salt water (which I doubt, given your location. ).

What kind of an exhaust system do you have? Waterlift, or something else? If you don't know, upload some pictures and we'll figure it out.

[Mo]

Easy to check stuff first.

I would suggest a quick compression test also. If you don't have a gauge here's the quick way. Remove plug, place thumb over hole holding downward pressure to seal. Have someone turn the engine over on the starter. Compresson should pop your thumb off. Do it for each consecutive cylinder.
If you have compression then move on and check fire.

Check to ensure fire to all plugs..and that each plug is firing and not faulty.Timing should not have moved unless someone was at it. If not a good blue spark at the end of the spark plug look at points and condensor...I don't think the problem is ignition but it should not be overlooked.

Now for Carb. Could be debris in a jet and starving. Might need a good cleaning...doesn't take long. Now for a few other fuel related ideas from experience.

> Couple of years ago I had water in my gas and it ran terrible. Sounded alright at idle and would increase rpm in neutral. Had very little... only sputtering under load regardless of forward or reverse....check your water separator for water.

> Check Fuel filters. Again, can cause fuel starvation under load. Ever have a car that ran well until you jumped on the gas or headed up a hill....I did...fuel filter was plugged...that was only about 30 years ago. LOL

As Ed suggested, exhaust blockage could very well be the problem...just make sure you check the easy stuff first. Once we attack the exhaust they normally have to be rebuilt as soon as we mess with them.

[Persistence]

Exhaust

Ok, I'm looking at Page 7-3 in the MMI Service and Overhaul Manual and my exhaust system looks pretty much like the drawing. (Sorry no pix, I'm 50 mi away from my boat at the moment). Anyway, there is a hose coming off the water jacket on the Port side of the engine. (That reminds me, we did replace that hose with a new one as it had a bunch of pin holes in it.) It bends down to a 'tin can' looking thing (water lift muffler?) affixed to the bottom of the hull and another hose comes out and runs to the rear. When the engine is running the exhaust water sort of 'burps' out - its not a constant flow - does that mean anything?

A little history - I partnered into the boat last April - the engine hadn't been started in a couple years so the PO and I did the following - new fresh water strainer, new elect fuel pump, new points, plugs and condenser (and yes we had a little trouble setting the timing but ended up with the motor running smoothly) we also replaced the original gas tank and fuel line to the elect fuel pump. We adapted a plastic 5 gal outboard tank for the replacement after findng one that was low profile enough to fit under the rear bunk (ps I don't like this arrangement - its a pain to fill it so I am planning to move it to the stern cockpit locker). After several outings the engine started having problems that we diagnosed as carb problems - yes - it had a bunch of gunk in the bottom of the carb bowl and in the process we messed up/ lost some rubber parts so ended up putting in a new carb kit and it ran pretty well for a few times then started having the problem I initially described in this thread. I do suspect the float level may be set a little high (re the black plugs).

I'm still concerned that it takes so much pressure to turn the prop shaft when in neutral but I'll do all the suggested checks next time I go out. Thanks for your suggestions - I'll be back to you with answers next time.

[Persistence]

fuel filter

Maurice, I read back over the thread again and realized I left something out. We replaced the fuel filter when we did all the other stuff(whole assembly) but it wan't a water separator type - just an inline filter - I'm not sure it has a water separator filter like the one shown on page 4-1). PO had replace gas line from tank to fuel pump earlier in the Spring before I signed on. I'll check it though, along with the other checks when I go out. thx Dave

ps. the A4 seems to use a lot of gas. I've had to add gas a lot for the little run time on it. I'd guess its using about 5 gal/hr - and thats with it running along at the slow rate rpm described - so yeah - probably a LOT rich - but with the multiple refills over the summer I kinda doubt water in gas - I'll check for a separator.
Thanks Dave

[Persistence]

Exhaust

Ed, the boats out of the water (see pix) now is there an easy way to check for an exhaust blockage? Can I remove the fresh water inlet hose and put it in a bucket of water? Is there an easy way to see if the 'tin can' (water lift muffler?) is partially blocked? Dave

[Mo]

Don't jump around too much.

Hi Dave,

Go through your systematic checks, compression, fire, fuel....you may find a combination of small variances that are compounding to cause you engines symptoms.

At this point I would check:
-compression....a cylinder or two without compression may indicate valve problems.
-check firing order on the plug wires and ensure it is wired correctly if they have been removed.
-check fire and ensure the end of plugs are getting fire...remove each plug individually and put the plug wire back on: wear glove and hold with insulated plier...ground the threaded / hex part of the plug on the head and have someone turn the engine over; look for spark at the tip.
-once above confirmed to be in order look at fuel system....pull the carb apart and look for a blockage...clean and blow it out. Look for signs of water and debris...take pics if you can.
-change filters again ...it is not uncommon to require multiple filter changes to clear system out if something got in there.

Some of these issues can be a combination of valve problem, bad plug or something simple like that, and carb malfunction. So the compression check should be your first thing then ensure ignition is working...ensure each plug is firing. Those checks will take about 20 minutes...After that start on the fuel system.

[ndutton]

Probably multiple issues

Dave,

I see four issues to be dealt with for starters:

Fuel tank and location
Your tank arrangement sounds dangerous. Filling below deck is verboten and what about the vent, is that below deck too? Relocating the tank to a locker solves neither of these issues and will add more head pressure to the float valve in the carb, another potential safety problem. You can run with a portable tank for testing but for your own safety and that of your partner and guests this fuel system needs to be refit properly. I repeat, from what I'm reading this sounds dangerous.

Possible exhaust restriction as suggested by others
You can either install a gauge in the exhaust outlet flange and report back or disconnect the exhaust from the engine and give it a noisy and stinky test. Note that the fumes emitted during this test are deadly so be very careful. Any change in performance suggests a restriction. 90% or more are at the water injection point immediately ahead of the waterlift (tin can you describe).

Possible prop shaft problem
Unbolt the coupler from the engine and test run. Again, any change in performance suggests a drive line binding problem. With mine attached to the engine and in neutral I can turn it by hand easily (Cat 30). Yours should too.

Fuel consumption
5 gallons an hour? Yikes and gadzooks ! You should be at 3/4 - 1 gallon an hour at cruising speed. I'd check this rate again after addressing the other three issues above.

Notice that all the suggestions involve systems external to the engine. As suggested by others, a compression test will indicate the general condition of the engine internally but you haven't said anything that makes me think there's an internal problem.

You should search the archives about techniques for running the engine out of the water, exhaust systems, fuel systems, hard starting and the like. There's a wealth of information available and much of it specific to the Catalina 30.

Next time to the boat please take tons of pictures, it really helps.

[Dave Neptune]

Multiple symptoms

Dave you have a classic what's first sinerio, so here goes. First a couple of questions. You stated that when put in gear the RPM drops to idle~OK~and you can move the throttle arm with no increase in power~~true?
Now for the carb, if you are using anywhere near 5 GPH something is way out of whack. My first thing to check would be the proverbial choke~be sure visually that it is opening and closing ALL THE WAY!! It would be very difficult to get that much fuel through such a small carb any other way unless the main jet is missing or backed out of its threads.
RE the tension on the shaft, it may be a bit tight but nothing the engine shouldn't overcome. If you get it spinning check for warmth, it should run warm to the touch but not hot. This is not your problem so I would put this part on the back burner for a while.
RE excessive back preassure I have a simple question~~did the problem manifest slowly or "here it is" all at once. Back preassure is something that takes time and slowly rear's it's ugly problems at the water injection point. A hose can colapse all at once though~just not that common.
What kind of filters are you using from the tank to the carb? What does the KRAP in the fuel bowl look like? How old is the fuel and are you using any additives?

Dave Neptune

[Don Moyer]

Hi Dave. Back in your post #4 you seem to be indicating that you have a rubber hose coming off the back of your manifold (what I suspect you're calling a water jacket) which "bends" down to your water lift muffler. I know that you're relying on your memory at this point, but if you really do have a rubber hose between the back of the manifold and the water lift muffler (and prior to the place where your engine cooling water is introduced), the inside of that hose is probably breaking away from the rest of the hose from the heat of the exhaust and be crumpling up on itself to create elevated exhaust back pressure. It would also explain why the old hose developed pin holes. Bending exhaust hoses can also create higher than normal back pressure.

[edwardc]

Ed, the boats out of the water (see pix) now is there an easy way to check for an exhaust blockage? Can I remove the fresh water inlet hose and put it in a bucket of water? Is there an easy way to see if the 'tin can' (water lift muffler?) is partially blocked? Dave

You can run the engine on land by moving the water inlet hose from the thru-hull into a 5-gal bucket, and keep this filled from a garden hose. DO NOT hook the garden hose directly to the water intake!! The pressure is too high!

But remember, the problem you're looking for is a restriction of the exhaust gasses, not of the water flow.

If you have access to the heavy rubber exhaust hose that goes from the water injection point to the waterlift muffler, you can remove it and try to inspect the inside of the hot section where the water is injected by shining a flashlight in.

But Mo is right. Anything more than that usually involves dealing with a heavily rusted hot section, and typically ends up with rebuilding it out of new parts. Black iron 1 1/4" pipe is cheap, but will only last maybe 5 years. Stainless is expensive, but will probably outlast the boat. It's also easier to disassemble. But we may be getting ahead of ourselves.

As Mo mentioned, if you have a Moyer exhaust flange, it's already drilled and threaded for an exhaust pressure gauge (which Moyer also sells). Just remove the plug and hook up the gauge for a definitive answer on back pressure.

Any back pressure in excess of 2 PSI is enough to start affecting engine performance. For the severe symptoms you're describing, I would think it would have to be WAY above 2.

Water lift mufflers are usually not the site of a blockage. BTW, the "burping" action of the water at the exhaust is typical of a normally functioning waterlift. It they tend to "Batch" the output, especially at idle.

[Persistence]

Wow

Wow - Thanks for so much information so quickly! Unfortunately, I won't be able to answer/investigate your questions, solutions, suggestions as quickly. I'll print off the whole thread and take it with me next time I go to the lake and start investigating.

The bit about the gas tank really concerns me - I guess I assumed the vented fumes would be pulled out by the exhaust fan. Since I'm going to change it anyway I'm thinking of getting a built-in replacement that I can hook up to the 'gas inlet' port on the gunnel and vent it however the old one was vented (the PO did the replacement and even though I've been under the bunk I don't remember seeing a vent line). Any suggestions on a replacement tank?

[ndutton]

If that was the P.O.'s installation every aspect needs to be examined and redone if necessary. One of our C-30 members has replaced his tank with a Moeller and he's happy with the product:

http://www.moellermarine.com/aftermarket/fuel_storage_tanks/permanent_tanks/

The following link is a boring read but every word pertains to your tank project. Following these requirements will result in a safe fuel system.

http://law.justia.com/cfr/title33/33-2.0.1.8.44.10.html

Thank you for taking my warnings to heart. I'm kind of surprised others didn't mention it too. Next time at the boat the tank needs to be removed whether you have the replacement in hand or not. Make sure all the electricity is off until its removal is complete. The risk of explosion is real.

This is about the worst previous owner story I've ever heard. Did your partner get a survey when he purchased the boat? I can't imagine a professional surveyor missing this.

[Persistence]

2 answers

Neil/Don, While I haven't been to the boat yet, I can answer a couple of your questions.

Don, the replacement hose off the manifold flange to the muffler can is one of those radiator hoses with the 'slinky' wire inside so I kinda doubt its collapsing. It came 'pre-bent' so the curve is natural down to the muffler. I'll take pix next time I'm at the boat and you can tell me if there is a Moyer flange on it.

Neil, Thanks for the urls. I went out and looked a both of them. The 12 gal permanent tank should work fine. I didn't find a price list so I called and left a msg w/their cust svc. Since the ad on the tank has all the various legal specs and certifications I imagine it meets the standards on the 'legal' website.

As to a 'Survey' - I[ve partnered on a c42 in the BVI and we were very serious about 'survey's there. This boat however... I doubt if its ever had a survey. It came from Clear Lake, Tex and I hear it was originally sailed on the Gulf from there. At some point it wasn't running, wasn't sailing, wasn't anything but a spare bedroom and then it was donated to one of those charities where the PO picked it up dirt cheap at an auction and moved it to Oklahoma. That was 7 yrs ago. PO was a mechanic (car type) and completely overhauled the A4 at that point, all the way down to the main bearings (which were frozen). He bought pieces here and there and made it sail again (no mean feat as I understand it). I came into the picture cause the boat is slipped at our sailing club and he hadn't paid dues in two years due to health/injury/unemployment. The boat hadn't been started or sailed for 3 years. My partnering came in the form of money to pay the boat's debts and bring it back to sailing condition (approx 7k). I've since bought him out completely. I've been sailing it twice a week since May and absolutely love it. I'll share some of the upgrades over on the c30 forum.

Thanks again to both of you for your valuable advice... Dave

[ndutton]

Yikes and Gadzooks #2

The exhaust you describe is also verboten. From the manifold flange there should be a metal hot section (see link) with water injection just above the waterlift, hose thereafter. The current installation has the potential for danger too. How in the Heck is water injected into the exhaust? Brutha, do we ever need pictures on this one.

http://dms.ntsb.gov/pubdms/search/document.cfm?fileid=234864&ntsbnum=DCA97MM012

Download the pdf found there. There are also excellent threads on this site regarding exhaust systems and plenty of C-30 specific info including pictures. Here's one of the better ones: http://www.moyermarine.com/forums/sh...hlight=exhaust

Right about now I'm thinking you're the luckiest guy in the world. Given these two installations by the previous owner I'd start looking elsewhere. Anything he touched is suspect.