Too much fuel

[97summit]

Hi guys

I was wondering if any one could help. We have three summits, all that use to burn the same amount of fuel. Now the 95 summit is going through DOUBLE the amount of fuel, so will not run right, it starts great but will not run around the 5000 to 7000 RPM range, (no power) Cannot find the problem and would appreciate the help.

Thanks Brent

 

[slomo]

float sticking or choke circuit stuck open possibly?

 

[Brucrew]

not running

Check the rubber boots between carbs and engine they may have cracks and are pulling air in DPM will compinsate by dumping more fuel. this happened to my 05 summitt

 

[97summit]

Thanks for the input:

We have checked, double checked, and triple checked the carbs, Both plugs are burning the same, so dont think there is a problem with the carbs. Have checked the rubber boot and they are in good shape.
Now we are wondering if it could be the seal inside the motor.

 

[2003Summit]

you can also check for junk and crud under the air screws. You can try running some fuel injector cleaner through it for one tank. Some it will clean the carbs out but not where the fuel can't get through and if there is stuff under the air screws it probably won't clean them out. Some times the o-rings and other seals get hard and start to break up and plug things. I would go through the carbs to make sure they are clean and seals all in good shape etc. Take them off and take them all apart, clean them if necessary, check all settings, check all jets (use and air hose to blow through them after you make sure there are no more parts/spring loose pieces to send across the room) put new seals in if necessary. Also check all dpm lines and make sure they are clean and clear. If you are still having trouble after all that, could be a failed component in the dpm.

I don't know how to trouble shoot a DPM but I know how it works. DPM works by adjusting the atmospheric pressure in the float bowels. It basically pumps in small amounts of air to adjust for altitude changes. It has a little computer controlled solenoid valve in the DMP manifold that cycles at 30Hz, the computer varies the width of the pulse to adjust the pressure. There is a mechanical pump down on the engine (kind of looks like a fuel pump) that pumps the air. Once of the hoses on the DPM is a vent line (ie. Vented to atmosphere and is the reference line), the ones going to the cabs are the vent lines on the float bowl, the other lines go to the pump. Some times there is no hose on the vent line, just a barb to put one. In any case (I don’t know if this is going to help you trouble shoot anything) if you blow or suck on the vent line it will massive change the amount of fuel the carbs are putting in. No something makes me thing their might be a vent line on the DPM computer as well, can’t remember. I guess one thing you could do to check if the dpm is working at all would be to hook a scope up to the solenoid on the DPM manifold, start the sled and watch the wave form on the scope while you change the pressure on the reference line. To change the pressure hook a long hose and use your mouth or a squeeze bulb (gently), you only need slight variances and any thing like a pound or more might seriously damage something.

Over fueling is going to carbon up your engine and leed to excessive piston/ring/cylinder wear. Don't leave it too long.

 

[OVERKILL 19]

If you have other summits laying around swap dpm,carbs,etc one at a time, cheap and easy trouble shooting. Reeds that warp when they get hot have bit me in the past. or crank seal ,can of brakeclean with a straw. Spray on seals joints while running lisen for idle increase to find seal leaks. Use sparingly you don't what to fogg in a ton of break clean,hard on pistons... Baby shots...LOL

 

[MoFoREVxp154]

Well....If its a 95-its got a HAC. Tis about the time the diaphram in the HAC is getting hard causing it to think the atmospheric pressure needs to richen up the flaot bowls. Find the specs of the same year/engine of a MXz and try to jet it accoringly and block off the HAC lines-would see right away if its running better-then find out EXACTLY how to plug tha carb/HAC out of the picture all together-or caugh up 500bone for a new one(if you can find a dealer with one-obsolete)Plus it could be a coil going weak. Will run but not enough hammer to keep a strong spark under the pressure of the combuston chamber. I had a 2001 500LC do that to me.

 

[97summit]

Thanks for all the help. Been busy and no time to look at it. But have some ideas now.. Thanks again