Ramjet frustration

[CapSS92]

Hi all,
I've got a Ramjet that I am installing for a friend and this engine is driving me nuts. Can't get the damn thing to fire. First time I ran it it would run real crappy, stumbling and misfiring. It would not run for any great length of time. So I changed the plugs. It ran semi decent for about 30 seconds and then died and would not start again. Removed the plugs and they are all black except for the #7 one. It's clean. Checked compression and it's at 160-170 all the way across. Checked the firing order and made sure the distributor pointed to the #1 cylinder. Fuel pressure is at about 40psi when it cranks. When it did run the last time, the exhaust got real hot about a foot away from the block hugger headers. Blistered the paint real bad. This is a brand new Ramjet 350 that had been sitting for about 2 years. It uses the MEFI-4 ECM. Any ideas that anyone has would be GREATLY appreciated. I hate that I can't even scan the damn thing without spending $200 for software.



Alex

[camcojb]

you need to verify timing, pointing at #1 still may not be close enough to run. Check for vacuum leaks, and make sure all the sensors are hooked up properly.

Will it start if you hold the throttle open a bit?

Jody

[CapSS92]

It does occasionally but I have to keep messing with it and even then it will die out eventually.

[Charley Lillard]

Really hot exhaust pipes would indicate retarded timing to me. Have you tried advancing the timing while it is running to see if it helps ?

[megaladon6]

IIRC the ramjet wants 50-60psi fuel pressure. i know some of the 350's, especially the early vortecs were hypersensative to fuel pressure.
also check your fuel volume, i've seen brand new pumps deliver good pressure but poor volume.
is the ecm calibrated for that engine?
is the lash set on the valves?

[Doug F]

Unplug the injectors and crank it over and get the timing close (10 I believe) before you fire it off.

[73z-6sp]

I feel your pain...man I hated that RJ when I first got it. I had the same issues you have. First and foremost, make sure the timing is correct. Then make sure your fuel pressure is correct and make sure your grounds are very good. I even went so far as to separate the grounds and attach them at different locations on the block. Then I added additional grounds between body/frame/engine. Not that it should matter but it was suggested to me and I was desperate.

In the end...it took two trips to Phoenix and Arizona Speed and Marine to get it to run correctly. They had to get in to the computer and tweak the settings. I hope you don't have to do the same but I fooled with mine for about a year doing everything short of standing on my head before I gave up and took it to them.

Best of luck! FWIW...it runs great now!

[CapSS92]

thanks to everyone for all the help and suggestions. Turns out the harness had some bad connections on it. A local guy lent mehis harness and I plugged it in and it ran perfect. So time to break out the ohmmeter. <G> thanks again.

Alex

[73z-6sp]

Awesome! Thats great news! Not that you have to chase wires but that you know the problem. Best of luck!