1997 challenger 1800 engine problem

[mustang1910]

i took the boat out for the first time and have an issue. bought the boat and had to do a top side rebuild on the port side. while doing that i cleaned the rave valves, put new plugs, changed fuel filters(not the carb ones). it starts fine at first. then when i rev it up it hits 4000 rpms and sit for about 4-5 sec then bounces from 5000 to 7000 rpms rapidly. if i leave it full throttle it will died and will not start for 10-20 mins like its not getting fuel. but when i pull the plugs they are wet with fuel. i also let it die and sit for 25 mins and started perfect. i tried very slowly pushing the throttle forward it will run alot longer but start to bounce at about 6800 rpms. i thought it might be cavitation but when it bounces it accelerates every time it starts the raise in rpms. any help?

 

[Gunsrunner]

Sounds like there could be an air leak, from the carbies.
Had the same once, where engine would rev by itself up and down with no control, gasket between carby and rotory valve cover bad!!
Could also be raves, what were the shafts like, is there a chance they could be sticking?
With the not starting, i find they can be harder to start when hot, i dont use choke when hot, but find 1 quarter throttle usually gets it started!!

 

[mustang1910]

the raves had carbon really bad. but i cleaned all of it off. replaced orings and checked the boot for tears, cleaned the small hole for them also. i will check for air leaks and recheck raves tonight. thanks

 

[mustang1910]

i took it out again today. resealed carbs to cover and rechecked raves. runs much better the only thing is when it runs above 6800 rpms, it will miss and then die after 10-15 mins. but will run all day long at 6700. any ideas?

 

[timmyboy76]

hey...if settings arent these, then possible conclusion, if not, i'd check the n/s(needle and seat psi pop-off), or rebuild the carb/s..:cheers:
1998 CHALLENGER 1800* 36psi- 40psi LOW- 1-1/2 HIGH- 0
btw, plugs gapped to proper spec???

 

[mustang1910]

checked the needle settings and the plugs are gapped correctly. but how do i check popoff pressure for the carbs in the boat?

 

[nswillin]

Hey mustang, check staff member JPX profile. He has a link of his carb rebuild and the way he tested the pop off. Of course pictures and all.:cheers: