Finally running, but some issues

[surfdogskier]

My 72 914/4 finally runs!!! First time in years. I never had her running. I am so pumped.

She idles really high so this could be a vacuum leak from what I read. I will search this out.

Unless I start her right away after shutting her off, she will not start back up. Evidently losing fuel pressure in the lines. It is a new pump that is pumping fuel but gone once the engine is shut off. I notice there are clear lines in sections. Why is that? Can I replace this one solid hose. I dont understand why the hoses have so many breaks in them. Seems to me this would only allow for areas for air leaks.

Also, my tach when connected back to the coil makes my engine shut down. Do I need a new tach or rebuild?

Last, based on the picture, this red wire when connected to the other wire causes the fuse to blow every time. I dont know what this is or what this part does or where that other wire is suppose to go.

[Dave at Pelican Parts]

Clear hoses aren't stock. Some materials aren't going to hold up to fuel for very long, so you should be careful about what kinds of hose you use for fuel.

The component that your red wire is coming out of is the Auxiliary Air Regulator. It serves as a built-in vacuum leak for when the engine is cold, raising the idle RPM. The single wire provides power to the heating element in the base of the AAR, which is what closes the valve. If the wire has a short to ground anywhere, it will pop the fuel pump fuse on the relay board, as it is hooked into the fuel pump circuit. I don't believe the red wire you show is actually the correct wire for it, though; my understanding is that the wire should be white.

Resistance from the end of the connector there to the body of the AAR should be on the order of 13 ohms. Yes, rather low, but not a dead short.

The AAR can be opened up (the "can" that contains it is folded over the "lid" and it can be peeled back with the right tools) and cleaned out, and the wire might be able to be replaced or at least have more insulation installed on it. Depends on where the short is.

If you suspect your fuel pressure is dropping, you can hook up a fuel pressure gauge to the high-pressure part of the fuel system. If there is an unused fitting on either of your fuel rails, you can put a hose on there and connect that hose to a gauge; if you don't have any spare fittings then you can make a "T" and swap that in for the cold start valve.

--DD

[surfdogskier]

Dave, thanks again for all your insight and help. I will do what you said and see if that helps correct things.

[Dave at Pelican Parts]

Oh, if the tach signal wire causes the engine to die, then the wire is shorted to ground somewhere. It goes from the coil to the relay board, into the main wiring harness, then up to the tach. Make sure the wires are connected properly (should be black with a purple stripe the whole way; the purple can fade though!) to the correct places.

--DD

[dr914]

aux air valve is probably shorted and stuck open that would account for the fuse blowing and the high idle

Originally Posted by surfdogskier

My 72 914/4 finally runs!!! First time in years. I never had her running. I am so pumped.

She idles really high so this could be a vacuum leak from what I read. I will search this out.

Unless I start her right away after shutting her off, she will not start back up. Evidently losing fuel pressure in the lines. It is a new pump that is pumping fuel but gone once the engine is shut off. I notice there are clear lines in sections. Why is that? Can I replace this one solid hose. I dont understand why the hoses have so many breaks in them. Seems to me this would only allow for areas for air leaks.

Also, my tach when connected back to the coil makes my engine shut down. Do I need a new tach or rebuild?

Last, based on the picture, this red wire when connected to the other wire causes the fuse to blow every time. I dont know what this is or what this part does or where that other wire is suppose to go.