lower voltage at fuel pump - 2.0 djet 1974 Options

[dax1969]

Morning,

I have a 2.0 djet fm 1974 with a complete rebuild engine. Wiring harness, plugs, injectors all new. 123 distributor with fixed curves, currently running at curve 2.
TPS board new and properly adjusted. CHT sensor is new. Broken thermoswitch so cold start valve is not connected.

Engine starts everytime, cold and warm - no issue
Steady idle
First kilometers car does not run very well, much beter when warmed up.
Once warm I have the occasional hickup at 3000 rpm while steady cruising.
Distributor is set at 27° btdc

When I compare to other 914's I've driven fm friends I feel like I am missing some power. It feels like engine is gasping for air or fuel at higher rpm ? (difficult to explain a "feeling")

All in all you good say, car runs fine ... but being a nerd I am still looking for better performance (IMG:style_emoticons/default/biggrin.gif)

I measure 14,3 volt at the battery but only 13.12 volt at the pump (located near steering rack). Could this voltage difference cause the pump to run slower giving less fuel pressure at full load ? the occasional hick-up ? The lack of "smoothness" ?

What to do to now ? Leave it like it is or trying to get more voltage at the pump ?

I cleaned up the relay board and relay sockets
I will replace the 25 amp fuse
I will clean the ground wires under the relay board
I know I should measure fuelpressure while driving but at idle it measures 2 bar

some suggest to put additional ground closer to the pump
others suggest to run new wire from battery to pump ?

thks your help
krgds
Dax

[bdstone914]

Ibdontvseexa oroblem with that voltage. It you suspect lack of fuel test fuel pressurs on thecdrivers side fuel rail. It sould be 32 PSI if i remember correctly

[dax1969]

Ibdontvseexa oroblem with that voltage. It you suspect lack of fuel test fuel pressurs on thecdrivers side fuel rail. It sould be 32 PSI if i remember correctly

Ok, thks yr reply. I have an inline fuel pressure gauge installed and at idle it reads the required pressure (2 bar, 29psi)

Read somewhere (I know, don't believe everything on the internet) that even with enough voltage at the pump to get it working, that a voltage difference between battery and pump of more than 1 volt can cause issues for the Djet.

krgds
Dax

[GregAmy]

First thing I usually think of when reading "DJet" and "hiccups" is electrical, specifically the pins on the relays becoming relaxed (compressed) and losing connectivity.

I'm going to sound like a broken record, but I had loads of DJet hiccups until I removed the fuel pump (and others) relay, slightly expanded the quarter-split pins with a razor blade, cleaned out the relay board holes with a small pipe cleaner, and put it all together with a light coating of dielectric grease.

The other big DJet improvement was lightly oiling the distributor weights with a couple drops of light oil at the top of the disty shaft (under the rotor).

Neither are the end-all answer, but both should be checked.

[emerygt350]

29 psi for the fuel pressure. That hiccup sounds like a worn TPS. A bad spot at cruise results in a complete cutout of the fuel system.

Why do you have the 123 set on 2? You might want to try 0 or 1. Do you have the advance hooked up and if so, where is the hose routed?

[dax1969]

First thing I usually think of when reading "DJet" and "hiccups" is electrical, specifically the pins on the relays becoming relaxed (compressed) and losing connectivity.

I'm going to sound like a broken record, but I had loads of DJet hiccups until I removed the fuel pump (and others) relay, slightly expanded the quarter-split pins with a razor blade, cleaned out the relay board holes with a small pipe cleaner, and put it all together with a light coating of dielectric grease.

The other big DJet improvement was lightly oiling the distributor weights with a couple drops of light oil at the top of the disty shaft (under the rotor).

Neither are the end-all answer, but both should be checked.

thks, did this preventive last year but will check again. Distributor is a 123 with fixed curves

[dax1969]

29 psi for the fuel pressure. That hiccup sounds like a worn TPS. A bad spot at cruise results in a complete cutout of the fuel system.

Why do you have the 123 set on 2? You might want to try 0 or 1. Do you have the advance hooked up and if so, where is the hose routed?

thks, TPS board is new and adjusted correctly - all clicks are there. Thing is that the hiccup is very occasionally, some sort of very short "cut-off".

The 123 is set to 2 basis the booklet and the number on my original Bosch distributor. The advance is hooked up at the front connection (the one closest to the distributor) of the throttle body.
Do you think curve 0 or 1 has a smoother advance for my engine ? Engine feels "flat" in higher revs... it looks like engine really needs to work hard to go to higher revs.

[emerygt350]

I like 0 and 1 but I haven't played with 2. I think the 009 had a better curve from what others have said but I doubt that is the issue.

I replaced my TPS board and within 2 weeks I was having that issue. I put my original back in and it stopped. Drove me crazy trying to figure out what it was since I had just put the new board in. If you have your original you might want to try it.