Hello all,
Great forum you have here, I like it.
I have a 78 Dodge Xplorer 220 (B200 360 2BBL) dual fuel with an EB regulator and 300A mixer which was converted 2 yrs ago (new parts) and did run nicely until a few days ago. Basic mechanical installation was done by a authorized specialist which allowed to keep the historical car registration (>30 yrs old) and I did the final setup and tuning myself.
Now she won't start cold and idling is poor (most of the time, on rare occasions it's back to normal).
Failing of cold start was the first symptom that's why I started checking and cleaning the start assist valve, and then all electric components, valves etc.
Also connected stuff directly to the battery for testing in case of voltage dropping during cranking.
Then I noticed that directly priming on the regulator doesn't help cold start either.
Power above idle on propane and also gas operation are normal.
Any ideas where I should continue investigating ?
Thank you!
-Frank-
IMPCo no cold start and poor idling
Re: IMPCo no cold start and poor idling
This is what is called back to basics time. You have analyzed pretty well all of the fuel system so it is time to look elsewhere. The bottom line is that you have to start from scratch. You say the system was new 2 years ago The one item you haven't checked or mentioned is the three screws that hold the mixer together accessed from the bottom in the recessed holes. These are the ones the nuts attach to the hold the air cleaner plate on. Theses can come loose when the nuts are tightened causing an air gap between the mixer body where the diaphragm gasket is.
Eliminating that it is time to return to basics. Most times the problem is not the fuel system but some other problem.
1. Do a compression test. The number one cause of poor starting and bad idling is the valves. If they are not sealing properly air flow is poor and improper mixtures result.
2. Check all of the ignition system including plugs gapped at .028 on Dodge and Chrysler products. New wires, cap, rotor and plugs.
3. Check the timing and make sure the advance system is working.
3. Check for vacuum leaks everywhere including the intake manifold, carb base, throttle shafts and EGR.
If it has the EGR still make sure it is not partially stuck open.
4. Have you adjusted the idle mixtures? You don't actually mention if you knew how. 300 mixers are very touchy and adjustments have to be made in small increments.
5. Test your manual primer by removing the vapour hose from the mixer, activating the electric lock off manually or by cranking the engine momentarily for a vacuum lock off. Turn the key off and then while listening at the vapour hose push the primer button. You should get a short blast of vapour propane from the hose and then it should stop. If propane comes out of the hose with the key off or there is no propane when the button is pushed you have a lock off or regulator problem.
The key is this. Don't automatically assume you have a propane problem. Check everything else prior to attacking the propane components.
Eliminating that it is time to return to basics. Most times the problem is not the fuel system but some other problem.
1. Do a compression test. The number one cause of poor starting and bad idling is the valves. If they are not sealing properly air flow is poor and improper mixtures result.
2. Check all of the ignition system including plugs gapped at .028 on Dodge and Chrysler products. New wires, cap, rotor and plugs.
3. Check the timing and make sure the advance system is working.
3. Check for vacuum leaks everywhere including the intake manifold, carb base, throttle shafts and EGR.
If it has the EGR still make sure it is not partially stuck open.
4. Have you adjusted the idle mixtures? You don't actually mention if you knew how. 300 mixers are very touchy and adjustments have to be made in small increments.
5. Test your manual primer by removing the vapour hose from the mixer, activating the electric lock off manually or by cranking the engine momentarily for a vacuum lock off. Turn the key off and then while listening at the vapour hose push the primer button. You should get a short blast of vapour propane from the hose and then it should stop. If propane comes out of the hose with the key off or there is no propane when the button is pushed you have a lock off or regulator problem.
The key is this. Don't automatically assume you have a propane problem. Check everything else prior to attacking the propane components.