troubleshoot a high end power lose

KRB64

KRB64

Member
Oct 12, 2006
785
Central Kentucky or Dale Hollow Lake
Boat Info
'76 SRV195 (our first) -> moved up to
'78 240 WE (now 4 sale because ->)
'82 260 DA shared
Engines
A Ford 351, a couple GM 350s and a Cummins 6BT to pull it all (W250)
Finally took the 260 out last weekend. Starts perfect, idles perfect, but stumbles when trying to get up on plane. Once there it will hold plane but still stumbles some. Not bad enough to show up on the tach but you can feel it. Worst is when trying to climb up on plane. Doesn't seem to want to rev out to the upper limits. Backing off the throttle seems to help some.

It had a nearly full tank over the winter with stabilizer. I've since added 20 gal of high test. Not checked the plugs or points yet. Ran fine when we put her to bed last year.

I'm thinking that since it starts and runs great at idle and low speeds that it could be the coil? Not real familiar with these carbs, could there be a high speed jet thats blocked?

Any ideas?

BTW, glad to see all the new interest in the 260s!
 
Yup I'd say ignition. Coil would be the first thought, is it original? Points plugs cap rotor wire could do it as well. Did you ever make the switch to the Electronic Ignition? I would also run some techron through your tank, to help clean out the carb and change all your fuel filters.

Keep us posted.
 
I 2nd the filter change. Engine could be starving for fuel at high rpm or under load.
 
I'll check the filters. Changed them last year and the carb filter was brand new looking. But I guess one tank of bad gas can mess all that up. You think the Techron really helps?

It does still have the original electronics, haven't lost the points yet. Cap, points and plugs are new. Wires aren't though. Not sure if the coil is original or not. Are marine coils any different than automotive? I could replace it easy/cheap enough I guess.

Thanks
 
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I do think techron can un-muck a dirty carb, but if you having leak down issues (hard to start) then the carb needs to be rebuilt. The two wells on the bottom of the carb (drilled and plugged by Rochester from the factory when the drilled the secondaries) need to be epoxy filled to stop leaking gas into the chamber when the boat isn't running.

Coils are the same but epoxy filled coils are supposed to withstand marine elements better then oil fille ones. I got the 30K volt petronix flamethrower coil (12v Neg) and it seems to work very well. It was only 30 bucks new. Make sure if you need a external resisiter, then you get a coil that works with one. Your old coil should say so if you need one of those.

Good luck!
 
I have never seen anything stating marine coils. That could be a problem, A safe marine coil that will not spark in the ER :lol: I'm using a MSD Blaster coil. Maybe its a Blaster 2 with the MSD marine ignition. Never hurts to change out filters when somethings wrong. Never know when that paper element inside could get restrictive. You could be dumping too much fuel at WOT also. Or not enough spark to burn it. Checking Spark plug color would help to determine that. I dont know what the CFM is on the stock 4 barrels. The secondaries looked huge on mine. I scraped mine 5 yrs ago after the floats stuck. Then put on a 600 CFM Edelbrock marine carb.
 
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Thanks for all the ideas.

She starts perfect and runs great at idle and trolling. You wouldn't know there was a problem until you try to climb above 3,500 rpm or so.

Yep, filters are "cheap", might as well swap and eleminate that.

I'll look in West Marine to get an idea of coil options.
 
Turns out ford made the 351W up till 2001. Should do a online search getting an idea if parts are available. That engine is suppose to have really good low end TQ.
www.MichiganMotorz.com sells the engine.

Strange, I was on a thread where someone is looking at a boat with a ford engine.
I checked the above site if they had fords. Clicked back and posted here.
 
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Our 195 has a Ford.

The 260 in question has the GM 350.
 
Have you checked the fuel line where it comes directly out of the tank ? I had the same problem and the screen was clogged at the tank.
 
Same issue with my 260 and screen in fuel line immediately before anti-siphon valve on top of fuel tank. Resoved this past weekend.
 
I'll check that screen as well.

Talked to my marine mechanic that does all the work I don't have the time or knowledge to do and he suggested checking filters and then the plug wires. Wires are the oldest part of the primary circuit next to the coil so I'll swap those and see what happens.
 
I highly doubt you have a screen by the tank or an anti siphon valve. The only filters on the old 260 were in the quadrajet, and a water separator.

Did you ever try a new coil? If its the original coil, then I bet thats your problem, but new wires would be a good idea as well.
 
BillyT0020 said:
I highly doubt you have a screen by the tank or an anti siphon valve. The only filters on the old 260 were in the quadrajet, and a water separator.

Did you ever try a new coil? If its the original coil, then I bet thats your problem, but new wires would be a good idea as well.
Click to expand...
Billy, I'm not sure about the screen but on my 86 there is an anti siphon valve. It's the barbed fitting that screws into the tank and the hose from the tank to the seperator runs from. I haven't had it off, but I know mine works I couldn't siphon through it when I changed my old gas out. I had to pump 60 gallons of old gas through it and couldn't get a siphon started. Then I looked in the book and it mentioned the anti siphon valve. My arms would have been a lot less tired and I wouldn't have sucked all those fumes had I looked in the book sooner. It keeps your gas tank from emptying into the bilge if you get a break in that supply line.
 
Yeah I don't doubt you have one on your 86 but that must have been something they put on in the later years. I had my original tank in my garage for 6 months before I sold it on eBay and there is nothing inside any of the fittings.
 
Stay away from the carb and fuel issues until you deal with electrical. 99.9% of all gas engine trouble starts there. What you are describing sounds like a breakdown in spark. It would most likely come from old wires, a bad cap and rotor, or points breaking down. A fouled plug will break down at high RPM but will remain fouled at the low end, too. I'd start at the distributor and work your way toward the plugs. Maybe $80 worth of parts total. While you're in the distributor, make sure the advance weights are freely moving and that the return springs on them allow them to fully retract.
 
My mechanic said to try the wires, that he didn't think it would be the coil - he knows more than me and is one of those good guys that doesn't mind to talk out a problem with you. He's plenty busy enough and doesn't mind a bit sharing his knowledge & advice.

The 260s seemed to have made a big design change after '82. Ours has the tank cover hatch so it'll be easy enough to unscrew and check out below there.

probably won't make it down there until the first of August though...
 
I would rather DIY and spend 30.00 bucks and have a fresh coil. Then pay someone else 100.00 per hr telling me its probably not the coil. For less then two hrs mechanics labor. New Cap,wires, plugs,filters,coil. Three hrs at the shop, Could have bought a nice new MSD ignition. And now I have spare backup parts :thumbsup:
Mechanics dont like me very much :huh::lol:
I will probably be on the mechanics CSR ignore list when my new 8.1 sensors start going bad. I'm already on that list :smt043
I would rater spend 100.00 on a IAC.Then pay a mechanic 100.00 telling me it might be the IAC. I probably should fill my lunch box full of them things.:wow:
 
BillyT0020 said:
Yeah I don't doubt you have one on your 86 but that must have been something they put on in the later years. I had my original tank in my garage for 6 months before I sold it on eBay and there is nothing inside any of the fittings.
Click to expand...
Pretty cool you sold your old tank. :thumbsup:
I was wondering about scrape alum for the old tank. PU tube is tiny. I dont see how they could fit a screen on the elbow that the anti syphon valve is attached.
Last month I put my old powertrain on CL. I had 9 responses the first day.
 
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