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AJ13734 · 02-02-2022, 02:03 PM

Family friend recently gave me his 1996 Damon Intruder with 59k-ish miles. Its sat since the beginning of covid roughly a year and ago and has the strangest issue I've ever experienced. I'm not an RV guy but I know my way around older cars and cars in general, having a '68 El Camino SS myself.

Intro: 1986 Damon Intruder 40ft or whatever on a Ford F53 Chassis with the Ford 460 (7.5L)

Issues:

• Doesn't start on it's own, period.
• Back Fires at 3500rpm and up, like you're making popcorn that's how consistent it is.
• Generator is a Kohler 7 gas, not propane, and doesn't crank nor start. (Might be so to the lack of a marine battery.)
• Pours Black smoke like a diesel that chugged all of it's DEF fluid.
• A/C and Radio don't work or turn on. Radio doesn't even light up?

What I've done so far

Motorcraft Spark Plugs
Spark Plug Wires
Distributor Cap & rotor
New fuel pressure regulator
Fuel pump because it has previously gone bad.
Oil and filter
Drained tank and added new, fresh gas

Soapy water tested vaccum lines and found a bad one that leads down to passenger wheel well, into a box. There's a other box right next to it that looks exactly the same but appears to be missing the connector piece where the one this tube goes into. (Pic below)

So far, I don't know what's wrong with it, the self test plug is shot and I'm waiting to rewire a new one into (bought it off eBay) I can start it with starting fluid and it starts right up and will run till it's out out of gas. It drives and I can get it up to about 60 mph, but if you take it above 3500 rpm It back fires and wants to stall. It idles a Little bit on the rougher side but doesn't stall or anything. It pours Black smoke out the exhaust like no tomorrow and I've read a bunch of stuff saying it's multiple different things and I've read similar posts to mine but none of them seem to be the problem I'm having, if anyone has even an inkling of an idea that would help, I would be super grateful

AJ13734 · 02-02-2022, 03:59 PM

Replaced that vaccum line and now it starts with the key but still pours Black smoke, started wondering if it might be a o2 sensor or something, they're probably dirty by now any ways.

tderonne · 02-02-2022, 04:56 PM

Looked at the fuel pressure regulator? If the diaphragm splits, it won’t reduce the fuel pressure at high manifold vacuum, and can let gas get sucked into the intake via the vacuum line to the regulator. It’s somewhat common thing. Easy to check by pulling the vacuum line off the regulator. But watch out, it can spray fuel.

AJ13734 · 02-03-2022, 12:31 AM

I have not, I know there's a small green plastic vaccum line in a loom on the top but it's a brand new fuel pressure regulator and I just assumed it would work. It's an ACDelco which is a relatively good brand (supposedly) but I'll check it. I did have to clean the fuel pressure regulator mating surface when I took the old one out because it rusted a little and prevented it from sealing, also noticed it cut two of the O rings so I bought a metric o ring set and found matching ones and replaced the o rings on the new one then made sure to use a bunch of vasoline when putting it in the second time. I sanded the surface down and the inside of the holes with high grit sand paper and then turned the key to accessory on to get the fuel pump to cycle gas through to clean it. One thing I've also noticed now that I think about it, I'm pretty sure my fuel pump still endlessly cycles in accessory on, is there another cause for that other than a bad fuel pressure regulator?

jimjenturner · 02-03-2022, 04:37 AM

Normally if exhaust is black smoke its normally to much gas going to engine. You might get a fuel pressure gauge and check the pressure at the fuel rail. Fuel might be getting thru pressure regulator since you had issues installing a new one. It should be between 38 and 42 at key on, and drop about 7 psi at idle and it should hold when the key is shut off. If you pinch off the return line, the pressure should go up to 75 psi or higher. Basically the fuel pump relay is supposed to be be energized when the key is turned to run to put pressure into the rails.

GypsyR · 02-03-2022, 08:50 AM

You don't really need the OBD plug to check the codes but it make sit easier. You can just jump the correct wires and count the check engine light flashes. In the early OBD days a "code checker" was a paper clip bent to connecto two terminals.

I wouldn't go too much further until finding out if the engine computer is complaining of a shorted MAP sensor or something obvious and easy.

tderonne · 02-03-2022, 09:46 AM

Man, I read your list, and went right past the new regulator. Still worth checking that it's working right.

AJ13734 · 02-04-2022, 11:20 AM

Regulator appears to be working there's a vaccum being pulled on the line coming out and theres no gas coming out when I pull the line off. It started yesterday but now it appears to be getting too much gas, which makes me wonder if I have dirty and or clogged open fuel injectors, but that doesn't make sense to me unless it's multiple which I guess could happen, still not sure where to go from here but I guess I'll continue checking stuff out. Now there is those two boxes, does anyone know if there's supposed to be more vaccum lines on them or something?

House Husband · 02-04-2022, 02:22 PM

Check the vacuum line to the MAP sensor. Located in the dog house, left side, forward. Hose connects to the rear of the throttle body housing. If the vacuum line is choked or disconnected on either end, the engine will blow black smoke.

Richard

AJ13734 · 02-05-2022, 10:42 AM

Are talking about the metal line with two rubber pieces on each end connected to a nipple because that line is rusted but not broken and I'm not sure if the rubber pieces are sealing correctly, they're a bit hard so I'll replace that line with a new rubber one.

House Husband · 02-05-2022, 11:35 AM

Quote:

Originally Posted by AJ13734

Are talking about the metal line with two rubber pieces on each end connected to a nipple because that line is rusted but not broken and I'm not sure if the rubber pieces are sealing correctly, they're a bit hard so I'll replace that line with a new rubber one.

Yes..........

Richard

MarvinG · 02-05-2022, 11:42 AM

Those two boxes in the wheel well where one was missing the vacuum line are your charcoal evaporative gas canisters. Your vacuum line goes to the front one, and a separate line simply connects the front to the back one.

AJ13734 · 02-05-2022, 12:50 PM

Quote:

Originally Posted by MarvinG

Those two boxes in the wheel well where one was missing the vacuum line are your charcoal evaporative gas canisters. Your vacuum line goes to the front one, and a separate line simply connects the front to the back one.

Do you have a picture of how it hooks up? Is it through the two that have no lines on them at all?