Engine miss when under load.

[Fishstick]

79 Pierce Arrow - Volvo 200D engine, 2 Jet Rochester carb, volvo 280 drive.

Put the boat in the water for the first time today for some water tests. Previous owner states engine rebuilt last year and by appearances, I'm guessing it actually was. All hoses, belts, bellows etc are new and the engine itself looks freash/clean and almost new.

She fired right up and ran fine at idle but when under load, there is an intermittant but very obvious engine miss. I got her up on plane, but she stumbled and backfired a couple of times and she felt very sluggish. Engine miss and popping started getting worse so I idled her back in to the dock.

Unsure if related, but I noticed the volt meter "bouncing" between 12/14 volts, and the fuel gage was bouncing. My jefferson CRT fishfinder screen was also bouncing in unison with the amp meter. The jefferson is wired direct to the ignition acc. (possible voltage issue perhaps)

The fuel in the tank is at least 7 months old and was at 3/4's of a tank when I picked up the boat 2 months ago. (possible bad/old fuel perhaps)

Shifts hard at the control lever (especially into reverse), but I'm guessing that's more of an adjustment issue. When the drive shifts into gear, it's very smooth.

Any ideas on where to start would be appreciated?

 

[Don S]

Re: Engine miss when under load.

First of all, NOTHING gets hooked to the ignition switch except the engine. You need to wire your boat for an accessory panel
You may have a loose/corroded/or dirty battery connection check them out.
The miss could be because of valve adjustment, bad plugs or plug wires, points, loose condenser.
What rpm does this happen at. I have seen some that start at about 1500 rpm and won't go any further because the spring on the points wasn't installed.
Might want to do a compression test also. And make sure the oil isn't overfull and being hit by the crankshaft ane aireating the oil.

 

[Fishstick]

Re: Engine miss when under load.

It made it up on plane and hit about 23kts before the miss started. I backed it down, and it ran smooth at idle, but when you put the throttle to it, the miss started again (1300 to 1500 rpm). The plug wires are new. I'll pull the plugs to check and run a compression check while I'm at it. I'll check the rotor/cap/points etc as well.

noted on the accessory panel.......

 

[JustJason]

Re: Engine miss when under load.

Just a shot in the dark.... but check your firing order while your at it.

 

[chiefalen]

Re: Engine miss when under load.

Bubba beat me to it. The ground, on the motor. Follow the neg cable to it.

 

[Don S]

Re: Engine miss when under load.

You may have a loose/corroded/or dirty battery connection check them out.

From an hour and a half ago.

 

[chiefalen]

Re: Engine miss when under load.

Don in all due respect and admiration for your talents, you didn't mention the ground.

Bubba pointed out that a circuit must be complete. We know what a bad ground can do but does the original poster know?

 

[Fishstick]

Re: Engine miss when under load.

Thanks to all for the valuable input. This is not my first boat by far, but it is my first I/O.....I will start with the battery connections, checking the ground at all points. The block was painted during the rebuild and I've already found a bad ground due to the paint on the drive lift unit circuit where it connects to the block so that's a good possibility. I'll still pull the plugs and run a compression check, check the distributer components and timing etc. For the accessories, I'll run a direct wire from the batt to a fused accessory block under the dash to run all the radios, depthfinders etc. It will be next weekend before I can launch again with work and the possibility of rain coming, perhaps two....but I will update when complete.

Thanks again......

 

[Fishstick]

Re: Engine miss when under load/update

Re: Engine miss when under load/update

Well....It don't look as though the repair manual I ordered is going to make it till next week and I'd like to get started on this Saturday if it quits raining. Don, would you happen to have the link for the specs (point/plug gap and timing) for the Volvo 200D?

 

[Don S]

Re: Engine miss when under load/update

Re: Engine miss when under load/update

Sure do, here is the link to the OEM service manual for your engine.
http://www.4shared.com/account/file/77796989/1532b1d4/AQ200_to_260_Service_Manual.html

Might as well have one for your outdrive too.
http://www.4shared.com/account/file/48536730/fa3b3311/280_to_DP-C_Drive_manual.html

 

[Fishstick]

Re: Engine miss when under load.

Thank you kindly sir.

 

[Bondo]

Re: Engine miss when under load.

there is an intermittant but very obvious engine miss. I got her up on plane, but she stumbled and backfired a couple of times and she felt very sluggish. Engine miss and popping started getting worse

Ayuh,...

Change the Fuel Filters,....

It sounds like it's going Lean.....

 

[Fishstick]

Re: Engine miss when under load.

Roger that, I'll add it to my list. thanks.

 

[Silvertip]

Re: Engine miss when under load.

Seven month old, untreated fuel that may have gathered significant moisture will also cause issues. Drain some off and check it for water.

 

[Fishstick]

Re: Engine miss when under load.

Thanks Silvertip. That's on my list as well.

I'll be getting back to this project on Thursday as the rain has started to clear. When I made it home from work today I had few minutes of daylight left and pulled the distributer cap. I noticed that that the previous owner had converted to an electronic ignition. My question is does the conversion do anything with the timing or should it remain at 8 deg BTDC as per the original specs?

 

[chiefalen]

Re: Engine miss when under load.

Timing is the same everything stays the same just no points.

You had it off the weights moving freely no shake to the shaft good and tight?

Me i would clean the carb, clean the filter in the fitting by the carb and the one in the fuel pump if you have one there, and run it on a external tank of clean fresh fuel, after i made sure the plugs are good.

Post how it runs after you do what i just posted.

Of course clean all the connections.

When you get a new to you boat all this stuff has to be done anyway, me i would have pulled the drive also, and looked inside and checked the impeller and seals but thats me.

I like everything right and i will never know till i touched, eyeballed and inspected everything, and still things can go wrong, believe me.

Good luck !

 

[Fishstick]

Re: Engine miss when under load.

Thanks chief. I've got a spare tank from the kicker and will do just that.

Not to add to much to the thread, but I'll be changing/checking the engine and drive oil while I'm at it. The book states that the drive uses the same oil as the engine (10W-30 or 10W40) which surprised me coming from a history of outboards.......Any recommendations on specific oil brands?

 

[chiefalen]

Re: Engine miss when under load.

You get 10 guys in a room and ask that question about oil and you will get 20 different opinions.

Opinions are like behinds everyone has one, no ones thinks theirs stink.

 

[Fishstick]

Re: Engine miss when under load.

Yea....I was afraid that was a loaded question subject to much debate. I digress and withdraw the question.

 

[Fishstick]

Re: Update/Engine miss when under load.

Re: Update/Engine miss when under load.

Pulled the ground cable at the block and found pretty red paint that was never cleaned. Found the same at the generator ground wire. Clean both block ground points to bare metal, the cable and reconnected. Replaced battery post and rewired the radio/fishfinder to an acc block routed to my second battery. Pulled all the gage wires, cleaned and reinstalled. Noticed the generator belt was very loose, so I took care of that.

Pulled the plugs and ran a compression check: #1 145, #2 133, #3 125, #4 140, #5 130, #6 125, #7 125, #8 145. All plugs were gapped appropriately and they look like they are burning good, tan - with the exception of the #7 which was black.

Timing by the book is 8 Deg BTDC, the prev owner had it set at nearly 16 BTDC so I reset it to 8.

Fuel filter at the carb was dirty, cleaned replaced. Also noticed that the four carb bolts to the intake were loose (not even finger tight) so I tightened them down. Drained off some fuel and didn't see any water in it. Gonna throw a can of sea foam in it and top off the tank with fresh fuel.

She turns over quick now (just tap the key and she starts right up) and is smooth at idle. The bouncing volt meter is now steady. Won't know for sure if the problem is fixed till I get her back on the water which will likely be Sunday.

Thanks for all the imput. I'll update further after I put the throttle to her.....