Gas MH won't start. Need help

[lg212]

Have mid 90's gas MH with 454 Chevy that won't start. It cranks good but doesn't start, no fire. Have replaced the coil, module, distributor cap and rotor. It has been suggested that it might be the pick-up coil in the distributor and we should get a new distributor.
Need suggestions other than a new MH

[turbojimmy]

The advice you've gotten is good so far. Last Fall, when leaving the campground for the last trip of the season, I moved my Allegro off of the leveling ramps to get closer to the sewer so I could dump it. After dumping, the 454 cranked but would not run. I put a screwdriver in a spark plug boot and held it close to a ground while I cranked. No spark.

30-minutes each way to an auto parts store for a new coil. I replaced the coil and same thing - no spark. After a few seconds I realized that I hadn't plugged the distributor back in after replacing it. Once plugged in, it fired right up.

So...check the basics first. Make sure you really don't have spark. Make sure you have 12V+ at the coil when you turn on the key. If starting fluid isn't causing it to fire, you can probably assume it's not a fuel issue.

Someone mentioned crank and cam position sensors. If memory serves, the engine will run if it loses CRANK position sensor signal. But it will not fire if it loses CAM signal. Don't quote me on that, though...

[77rollalong]

check the pink wire at the distributer for 12V in both run and in start key position. if its there then check the pickup coil wires that hook to the black ign mod, i think yellow and green? cant remember the resistance it should bee off hand but could look it up. if not mistaken your coil sits into the top of the cap, there is a button that goes from the bottom of the coil to the top of the rotor in the cap , make sure its there,,

[Matt_Colie]

LG,

You have lots of good responses here. While some may be better than others, they all have one thing in common. Do the diagnostics. Always start with the basics.

You say you tried starting fluid. (I have seen so many good engines destroyed with that stuff that we don't even have in our our shelves.)

Did you actually check for spark?
Like pull a wire (you can't pull the coil wire, it doesn't have one), put a phillips screwdriver in the boot and hold it near metal - like 1/4" - and crank? If you can't see a good hot spark, find out why. In the GM books, there is a diagnostic tree for HEI.

If you do have good spark, now take you timing light. (If you have an engine with a distributor, you should have at least access to a timing light.) And hook it to any plug. Open the airfilter housing and point it at the injector body. When you crank, there should be fuel coming out of one of the injectors. If you move the pickup to the next plug in the order you should now see fuel from the other.

If that all works as it should, you may have much bigger problems than you can fix in the driveway.

Matt - a refugee from the Detroit engine labs

[Sam_Spade]

lg212 wrote:

Need suggestions other than a new MH

Have you considered PAYING an experienced mechanic for his expertise ?? That might be cheaper in the long run.

[1995brave]

Was any work done to it before you tried to start it? Check your wiring, mice or squirrels could have chewed them. Check for voltage at the connector for the distributer should have 12volts, if not check your ignition switch.

[DrewE]

midnightsadie wrote:
X2 stop throwing money at it, #1 you have to have spark # 2 must prove you have fuel.

#3, once you know you have spark and fuel, the two must be timed properly in relation to each other and the engine internals. Are the wires correctly put on the distributor terminals? Is the timing belt/chain set properly (and unbroken)?

There's really not much else that can keep a gas engine from running at all.

[midnightsadie]

X2 stop throwing money at it, #1 you have to have spark # 2 must prove you have fuel.

[donn0128]

Do you have spark? Its easy enough to check. Throwing parts at the problem is not the way to go about it.
An internal combustion engine needs two things, fuel and spark. No fire means one is likely missing.

[lg212]

Seems to be getting fuel. Tried starting fluid but no luck.
Thank you

[rgatijnet1]

You might try using an OBDII meter to see if any fault codes are showing. I believe that you have both cam and crank position sensors that can fail.

[ksg5000]

Is it getting fuel? Older rigs have fuel pump and fuel filter issues.