My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

[tmlavigne]

My 1975 45hp Chrysler model 454BC sat for about 10 years with a bad lower end. Fixed it after 10 years of procrastination. Used the boat a few times and now the engine has crapped out. It was beginning to idle rough the more that I used it and then it began giving lots of problems. Here's the info:<br /><br /> fuel ball is good, lots of gas in the sight glass at the pump and I can squeeze the ball and get fuel to come out the hose at the carb, all new fuel hoses, cleaned out the carb and it worked good. Suddenly it won't start at all, I crank it over and I get some gas build-up at the carb but it doesn't seem to be getting to the plugs. I checked the lines that run off the carb (the ones with the check-valves in them and they were dry and empty) and the plugs have spark but they both don't seem to be getting any fuel from the Carb. When I crank it over it just backfires every few seconds and then the whole engine seems to lock. I have to re-start cranking it again and then it turns over fine although it seems to really be drawing a lot of juice from the battery. The battery was good and fully charged. I think that it is a fuel problem since the plugs should be soaked after all the cranking, right? Where do I begin? Please give a frustrated guy some more knowlegeable advice and it'd be greatly appreciated.

 

[scotiany]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

The 2 things I'd do first. Take the carb off,disassemble, SOAK in carb cleaner or gas and blow out passages with compressed air, get a carb repair kit from here at iboats or NAPA and rebuild it. The kit comes with good instructions. It sounds like the needle and seat valve is worn out. It's less the $15. Get a fuel pump kit at iboats or NAPA and change the diaphragm and the cover gasket. At this time , I wouldn't go any further into the fuel pump. Don't overtorque the screws on the pump cover. Use loctite or such. If this doesn't help, you may have worn reed valves but, I hope not.

 

[nmbr1ddy]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

What are reed valves?

 

[tmlavigne]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

I don't think that it is the fuel pump because fuel is getting into the carb and I soaked the carb in "dunk" at the beginning of the season. I don't think it's the needle valve because I can see the fuel accumulating in the port of the carb. It seems to be a problem between the carb and the cylinders. A plugged carb still wouldn't explain the cranking issue. If the reeds are bad, would that cause the engine to crank and then suddenly lock? It starts cranking again as soon as I re-try. I'm stumped..

 

[eurolarva]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

I am with scotiany on the carb thing. The motor sat a long time with gas probably in it. Gas will varnish over a year and you mentioned 10 years. I am not sure what dunk is but if it is industrial carb cleaner you probably did more harm than good. Chrysler carbs have a protective coating on them and the manuals say not to use carb cleaner. The newer carb cleaner is EPA friendly and it only about 10 percent the strength of the industrial stuff. Here in Minnesota we cant even buy it without a license. You should get a rebuild kit and remove the welsh plug and clean all the small orifices with a wire and spray carb cleaner after soaking the carb in gas overnight. Use a combination of wire, carb cleaner and compressed air but keep the air pressure under 30 psi. Also take your float and put it in a bottle of gas and push it down in the gas to see if it fills with gas. It could have a leak in it. Also take the mixture adjust screw out and look at it with a magnifying glass. If the tip is scored or dinged you will need to take some emery cloth and lightly sand these grooves out. Spray carb cleaner in that hole and blow it out with air as well. When you remove the carb spray the reeds with a healthy blast of WD40 as well. Then do the fuel pump. Total cost to do this stuff is around 50 bucks. Even if it dont improve the motor it is something that needs to be done. Make sure you check out the FAQ forum for winterizing. This is a must so you dont have to take the carb apart on a regular basis. Drain the gas and fog the motor will make it start right up in the spring without any problems and next season you will be taking a tackle box with you instead of a tool box.

 

[tmlavigne]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

Thanks for the info guys. I'm pretty sure that it is not the carb because it went from good to bad over the course of a few minutes. I've soaked the carb in "dunk" before and it didn't seem to kill it. It's a strong cleaner recommended for carbs and stuff. Anyway, I've got another carb off another parts motor and I'll change 'em up and see if there's any difference. Both carbs are clean and were soaked. When I'm cranking the motor I'm getting some backfiring through the exhaust and also back through the carb sometimes...?<br /> If the reeds have something wedged in them keeping them open wouldn't that cut off fuel to the cylinders since there would be no suction? and also allow a backfire through the carb?<br /> I might sound like a dummy about this stuff but I'm still trying to figure this problem out and I'm not the most knowledgeable guy on outboards...<br /> Any more advice that would be usefull would be great. Thanks guys.<br /> A fishing trip to the middle of the river instead of sitting in the boat with it tied up to the dock fishing would be a lot more fun these days... really.

 

[BF]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

Are you sure it's a fuel problem? Maybe it sheared the flywheel key and the ignition timing is way off.<br /><br />If your flywheel has timing marks you could check it with a timing light while cranking it over.<br /><br />Just a thought... <br />Brent

 

[scotiany]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

BF, that was my thought too. But then I remembered when I sheared a flywheel key back in '78. The engine stopped cold. I agree though that it's something to check into.

 

[TOHATSU GURU]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

The only thing that will cause a backfire on this model engine is a broken flywheel key. That will also cause the fuel to spit back out through carb. Although you can also get carb spitting with a broken or chipped reed.<br /><br />Elvin<br />AvalonProGrp<br />InternetOutboardsUSA

 

[tmlavigne]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

Hey guys, thanks for the info. Actually, after I pounded the flyweel off with a pick axe (it had wrecked my harmonic balancer and the puller was useless...) I saw that a small bolt had come out of the condenser and got chewed up and distroyed a bunch of other stuff. I don't know why it was spilling fuel out of the carb because it wasn't flooded but anyways, I've got it running again after a new pick up condenser and cleaning up the plate that everything sits on. I couldn't get the throtle to work properly and that had been the problem. Too much crap stopping the plate from moving and jamming the throtle.<br /> Anyway, thanks for all the advice. I checked the reeds and they were good and the fuel pump was replaced but obviously that hadn't been the problem either.

 

[eurolarva]

Re: My 45 hp Chrysler is puking fuel at the carb and backfiring and won't run

Glad you got it fixed tmlavigne. Hope it stays that way. One good thing out of all of it you gained a ton of valuable information on working on the motor.