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'81 Chrysler 360 carb / fuel issues

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On Sacred Waters

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Just purchased a Trojan F32. The quick sea trial went ok with port eng back fire through carb on throttle up a few times. We brought it across Lake Mich. after topping off tanks. ! engine just flat out dies 4 min on the lake, 2-4' condition. 690 houts on it but long blocks were installed 100 hrs ago ( 7 years ago). Boat had little use, mostly idle time on river. 1/2 way across, we lost the other engine (aprox 1.5 hrs running time) It did restart but could not get RPM's up and it even died at an idle. Came across on 1 engine and started the dead eng for docking. Went through carbs, no real issue seen - 1 carb was just replaced a year ago. Timing at 8 degree. Seems to have good fuel flow. Filters,caps, plugs rotor all new. Now, we have a hard time just getting the engines off idle speed, 600, no load. Seems like the more we played, the worse it got. Now,a day later, 1 engine seems to ramp up ok but with back fire through carb a few times and the other falls flat after 1500, no load. Must play a lot with throttle to get it over 1500. We have no "real " history. The AFB's have matching tag # 9263S, the book states it should have 6212S. We need to pull a fuel sample next week to see how clear it is. Doesn't smell right, but not real bad either, we are industrial engine mechanics. Also going to try running them off a separate tank of known good gas. With timing light on at 2000rpm we were 18 btdc. The timing mark was stable and constant. Any other suggestion?
 
On Sacred Waters said:
........................... Timing at 8 degree. Seems to have good fuel flow. Filters,caps, plugs rotor all new. Now, we have a hard time just getting the engines off idle speed, 600, no load. ...................
Click to expand...

Is 8° specified on your engines?
This from a Chrysler book.............
 

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We need to pull a fuel sample next week to see how clear it is. Doesn't smell right, but not real bad either,
Click to expand...

Ayuh,.... My guess is, That's the problem,....

Flush the fuel system, 'n try 'em on a can of known fresh clean gasoline,...
 
Thanks. I have seen other posts that the timing should be set at 8 deg. The book we have says 2.5deg. but questioning the year. We did not hear any "pining" when the engines were initially ran at 3000 under load so didn't really question the 8. Thanks
 
No it was not. It ran OK with the old fuel without andy pinging and held a load. We are going to run it off a separate tank with known good gas. And yes, we added about 40 gal of fresh gas to the 30 gal or so of old.
 
bondo said:
Ayuh,.... My guess is, That's the problem,....

Flush the fuel system, 'n try 'em on a can of known fresh clean gasoline,...
Click to expand...

OK, Ran engines on separate fuel source. We may have had filter problem. Pumped a gal. of gas out of each tank through the fuel lines, clean and appears good. Went through both carbs and brought the fuel level higher than specs call for. Now, idles ok, but when you bring up the RPM, at 1800 both engines fall flat. If you play with throttles, it will go up. I'm really questioning the pump shots. Before both seemed to idle rich, now seems ok. Both engines are doing the same thing
 
Sounds like excess water in filter/seperators. Remove carefully and upend into large glass jar. Look @ color (should be clear and lightly tinted) and the wait about 20 mins and see if the water forms a layer in the bottom of the jar. Mixing new with old fuel, not a fix, unless old fuel is a very small amount. Marine stores sell a strip you can put in tank (possibly thru fuel gauge hole if fuel fill line not direct and short...do not reuse gasket) that is supposed to be able to absorb water. I've not experience with this product, just relaying what is says on the package label.
 
We replaced 1 carb with the edelbrock 1409. Big difference. No popping back on throttle up, ramps right up. Now, I think we have a fuel pump problem. Looking into electric pumps but need to find out pressure an flow rates needed.
 
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