Troubleshooting a 1.7 with hunting idle, Buddies car Options

[JRust]

Okay so I met a guy a while ago who had painted his uncles 914. I talked with him quite a bit & he is a good body/paint guy. Only saw pictues of the black 914 but it looked beautiful. Anyway he is having trouble getting the 1.7 tuned. Here is what he sent me

"The car does not idle right it goes up and down and i think it is the fuel pump. I think l i am going to get a new pump and see if it does any good but if i bought one i was going to need to get one bigger for the carbs? correct ? Should i get one first to see if it will do the job? What do i get? Once i drive it a mile or so it starts cutting out at higher rpm's. That is why i think it is the fuel pump ...I already changed all the vacuum hoses and all that stuff ...ANY INPUT????? "

The hunting idle sounds more like a vacumn to me. He says he replaced all of those though? Just some suggestions I can give him to check out would be great. Thanks

[r_towle]

First up...tell him to join the club so he can get direct information and diagnosis.

If its Djet FI then he will fall on his face when he sees the price of a pump...slow him down, its not the fuel pump...

First, change all the vacuum lines.
Second, get an inline fuel pressure gauge so he can see the fuel pressure. It gets mounted between the inlet line and the fuel pressure regulator, not after the regulator.

Third, give it a good tune up with new points, plugs, wires and cap.
Set timing and dwell with meters.

Djet hunts at idle for a few reasons...
CHT, Cylinder Head Temp sensor
MPS, Manifold PRessure Sensor
TPS Throttle position sensor.

Lots of simple tests to check all of these parts.

Rich