Rv Will not start.

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Liuhisn

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Oct 5, 2018
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Hello I have posted in the past about my Rv that turns over but will not start. It is a 1995 Dolphin with a f53 super duty engine. I have replaced the fuel, fuel pump, fuel filter, spark plugs, injectors cap and rotor and fuel pressure regulator! It still will not start. My question is, is there a second fuel sending unit attached to the frame to increase fuel pressure to the injectors? I have tried everything else and besides collapse lines, I don?t know why it won?t start. Help!
 
No fuel pump on frame rail from factory. Collapsed line improbable with pump in tank. Are you saying you?re not getting pressured fuel to the injectors? That fuel pump runs for a couple of seconds when key is turned on? That it will try to start or run on carb cleaner, propane, starting fluid, and ect.
Sometimes you can check the fuel pressure with an old tire gauge at schrader valve on fuel rail. Or, just depress valve core and guess at pressure. Watch your eyes.
If you suspect no spark, could be bad ignition control module. Easy check. Unplug spout ( spark out) jumper. If engine starts, bad icm. Spout jumper located at diagnostic port. Google.
 
To start and run, it's always fuel, air/compression and spark. Spark is the easiest to check for and eliminate, except it must spark at the right time. Air/compression can be anything from a plugged filter to burned valves or cams not turning. Previous poster covered fuel well, but flooded condition is possible if the injectors leak down like the ones do in mine. I'd do a search for "(your engine) won't start solved."
 
That should be the fuel injected 460, right?  Good news is that those are still relatively simple engines with relatively simple engine management.  As said above, you need three things in your fire triangle: fuel, spark, air.  Air is, generally speaking, going to be covered with compression and leak-down checks, so let's hold that off until the end.  Fuel and spark are easier to check without any special tools.  First thing to check is that you have a good, strong battery.  It's unlikely, but possible that a battery that is just weak enough to not let the engine start could rotate it enough to sound "normalish".  I doubt that's the problem, but let's rule it out.

Next up is to be concerned with spark.  I think that has a regular distributor with a rotor and cap feeding a single coil to the spark plugs.  If you have one plug that isn't firing, the other 7 should get it to run (albeit poorly), so it is unlikely that your problem is a single plug wire or plug.  Pick a plug, any plug, and pull it from the head.  Using either a testing tool that you can get from any FLAPS or using a wire with alligator clips connect the negative electrode (the bent metal part at the bottom) to a really good ground.  Plug the...  uh, plug back into the plug wire and make it nice and dark around the spark plug.  Also, be sure you don't have any flammables nearby.  Get an assistant (or use a remote starter with the ignition key in the "run" position) to try to start the engine and watch the spark.  You should have a good, regular blue spark between the positive and negative electrodes.  You can also try this step with a brand new or known-good plug of any type to avoid having to pull the plug from the engine, just make sure there is a really good connection.  If you do not have good spark, then plug the spark plug directly into the coil itself and try again.

If you get good spark off the coil itself but not off of the regular plug wire, then I would replace the dizzy cap and rotor button.
If you get poor spark directly off the coil, I would check the wiring to the coil, verify a good ground, and if all that checks out, try a new coil.
If you have good spark off the plug wire right out of the gate, then it's time to move on to fuel.

I don't know my old school Fords as well as the SBCs and the modulars, but I think that in '95 that would have been multi-port fuel injection, which means it's unlikely that all the injectors have failed at once, so if there's a fuel issue it is probably upstream of the injectors.  There should be two fuel rails - one over hear head - that have the fuel line from the pump as an input and 4 injectors as outputs.  Disconnect the fuel line from the fuel rail (either side) or if you can find a common connection that tees off to each rail, that will work as well.  Put that in a bucket, watch out for ignition sources, and turn the key to the "run" position.  You should get a very healthy splash of fuel from the priming pulse.  Disconnect the feed wire from the coil to the distributor cap and isolate it to prevent sparks and attempt to start the engine.  You should get a pretty decent quantity of fuel.  This isn't a great test because we're only checking for volume, not for appropriate pressure, but I'm trying to rule out things as quickly as possible without needing any special tools.

If you don't get a good deal of fuel, find the relay for the electric fuel pump and jump it.  You should start filling your bucket with fuel pretty rapidly.

If there's no fuel during regular cranking/priming, but you get fuel when you jump the relay, try a new relay.  If you have the same result with a known good relay, then the fuel system is good, but the ECM isn't telling the fuel pump to fire up which could likely be a crank sensor or whatever they used for a tach signal back then.

Obviously, if it works with a new relay, replace the relay and go camping.

If you get no fuel under any of those circumstances then it's likely that the fuel pump is burned out or the fuel filter is seriously blocked.  Same if you get a very weak flow.  I had a pump once that was intermittent - I would have great flow when I jumped the relay, but after a few seconds of filling a coffee can with gasoline the flow would sputter and stop for a bit before resuming.

If you have good fuel flow and good spark you'll want to try a fuel pressure test and a leakdown test.

Another quick test to see if it's fuel-related is to grab a can of ether and spray some down the throttle body.  If it coughs on that, or better yet, starts for a moment, then spark is okiely dokely and you need to focus on fuel.  If it doesn't even cough, it could still be fuel-related, but it's likely a spark problem.
 
If you have a throttle body instead of multi port injection the starting fluid is what I'd do first. Otherwise you probably have a mass air flow sensor that could be damaged by starting fluid. In which case spray it after the MAF. If it does start on starting fluid look at fuel delivery problems first.
 
was did a great job explaining what to do. Anecdote: My RV quit once while sitting at a red light. Hours later I found the two screws that kept the rotor inside the distributor had backed out. So while I had spark, it wasn't timed with the engine.
 
there may be a fuel pump relay, I had an issue on an older ford where the oil pressure sensor was bad and because of that the fuel pump relay would not engage, check your manual for where fuel pump or starting relay may be, you should feel a click if it activates
 

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