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UND172's avatar
UND172
Explorer
Mar 18, 2014

Ideas? help? First motorhome , fuel issue, 81 P30 454

So, I knew when I bought her that I would have to put a substantial amount of money toward issues I would come across, she is old.

That being said I have a very general question regarding the process and where I should begin to diagnose and fix a problem that has arisen.

When I bought the 81 p30 454 pace arrow (80K), she ran great all the way home, 260 miles, outside temp 5degrees Cold!. Then, a week later I fired her up to drive to a shop 70 miles away, I did let her warm up for a half hour, (outside temp 22degrees) as I was driving immediately I could tell she was misfiring, I could break 55mph, then she got worse and felt like I lost another cylinder, couldn't break 45mph.

My question is where should I start, from the tank forward, or start with typical plugs, wires, cap and rotor?

does anyone have experience with these old rigs and my issue? anty advice would be helpful.
  • I had an 84 that had a bad hall effect transistor, I think that is what it is called in the distributor. It felt like I was running out of gas. Since you are carbureted and the temperature was around 22 degrees, I would suspect that your choke may be sticking.
  • gswcgi wrote:
    I had an Allegro, 1985, 23' with a 454. It suffered from massive vapor lock issues. Since I bought it new I called old man Tiffin and he finally relented and sent me an extra fuel pump to install in front of the fuel tank which solved the problem. The 454 was a real Turkey. Went thru 2 sets of manifolds until I changed to stainless Steel. It also burned up spark plug wires. Tiffin attributed all of these problems to the engine not getting sufficient airflow/intake.

    Not getting enough airflow would be the responsibility of the coach builder. That has been a constant problem with some builders having heat problems and others having no problems with the same chassis.
  • I had an Allegro, 1985, 23' with a 454. It suffered from massive vapor lock issues. Since I bought it new I called old man Tiffin and he finally relented and sent me an extra fuel pump to install in front of the fuel tank which solved the problem. The 454 was a real Turkey. Went thru 2 sets of manifolds until I changed to stainless Steel. It also burned up spark plug wires. Tiffin attributed all of these problems to the engine not getting sufficient airflow/intake.
  • This might help

    454 gas issues

    Do a web search for 454 gas issues, there is a wealth of information out there. I think my parents had one with the vapor lock problem.
  • Might have water in the gas. Was it sitting before you bought it?
  • My P30 Had a fuel filter in the carburetor that gets neglected it also had a electric fuel pump that caused some issues.
  • Start with the plugs, wires and cap/rotor. Our 454 had several burnt wires that were not in their clips and were bouncing on the exhaust manifold.
    There is probably a fuel filter halfway up the passenger side, inside the frame rail, that should be changed also.
    Good Luck!