D-Jet troubleshooting Options

[saigon71]

Could use some ideas…

Background: Car sat idle in a garage for six years - 37K miles. Engine was free. 2.0 factory d-jet. I adjusted the valves, installed a new fuel filter, changed the oil & put some gas in it. It fired up but had a very high idle.

Since then, I have done the following:
-New plugs & wires
-New distributor cap, points & condenser (rotor was clean)
-New air filter
-New alternator & voltage regulator - tested good
-All new vacuum lines from AA
-New intake runner gaskets and manifold to head gaskets
-Tested all FI components except the brain. Replaced AAR and MPS with good used
ones, bench tested each before installation. MPS holds 20 in HG and electrical tests
were within limits. Replacement parts are compatible based on this site:
http://members.rennlist.com/pbanders/djetp...tm#troubleshoot
-Tested fuel pressure - dead on factory spec of 2.0 bar
-Dwell well within specs
-Set timing dead on at 27 degrees BTDC with distributor lines plugged and disty at
full advance
- TPS set according to the picture I found on this site
- New plenum to intake runner gasket
- New cold start valve gasket
- Tested PCV Valve
- Plenum inspected – no holes found
- Throttle body removed & thoroughly cleaned

At all ambient temps tested (50-70 degrees F), the car fires right up but stalls almost immediately…this happens twice. Tapping the throttle does not help. On the third start, the car stays running and idle varies between about 800-1200 RPM. After about 10 minutes, it settles in at about 950RPM or so. Besides this, the engine runs great, has plenty of power and pulls hard in all five gears. Is this as good as it gets or am I missing something. Thanks in advance.

Bob

[SLITS]

In the D-Jet system, the operating pressure is about 28.7 psi, measured with the car running. When shutoff, the pressure drops to about 20 psi and holds for a period of time for hot start situations.

The fuel pump, when running, should hit the 29 psi rapidly, as in a couple of seconds. If not, then the pump is either going south or you have a restriction somewhere in the supply lines.

On shutdown, if the system doesn't hold pressure (20 psi) for a fair amount of time, it is possible the the pressure relief valve on the pump is not holding.(on a 911, fuel pressure is held for 20 mins). This would also cause a slow rise in fuel pressure as the pump is bypassing fuel pressure to the return line. The pressure relief and checkvalve are one in the same on a teener pump. Two springs, seating a ball under one silver cap.

Food for testing the fuel system.

[saigon71]

In the D-Jet system, the operating pressure is about 28.7 psi, measured with the car running. When shutoff, the pressure drops to about 20 psi and holds for a period of time for hot start situations.

The fuel pump, when running, should hit the 29 psi rapidly, as in a couple of seconds. If not, then the pump is either going south or you have a restriction somewhere in the supply lines.

On shutdown, if the system doesn't hold pressure (20 psi) for a fair amount of time, it is possible the the pressure relief valve on the pump is not holding.(on a 911, fuel pressure is held for 20 mins). This would also cause a slow rise in fuel pressure as the pump is bypassing fuel pressure to the return line. The pressure relief and checkvalve are one in the same on a teener pump. Two springs, seating a ball under one silver cap.

Food for testing the fuel system.

Re-connected the fuel pressure gauge. Fuel pressure jumped almost immediately to 30 PSI upon cranking the engine. Dropped to 20 PSI immediately after the starter dis-engaged. Leakdown from 20 PSI was as follows:

30 sec - 15
60 sec - 11
90 sec - 8
120 sec - 6
150 sec - 4
180 sec - 3
210 sec - 1
240 sec - 0

What are your thoughts? Fuel pressure drops to zero in about 4 minutes. Check valve?

Thanks,

Bob