[Brian Fuller]

1978 SC. Car was purchase 3 years ago. I was able to drive it home but remembered it did not perform well. Had a cold start problem but drove it 15 miles home. Pulled the engine, cleaned everything. Put back together and now tried to start 3 year ago to the date.

Cold start problem remains an issue. Car starts but if you press the gas pedal, the engine bogs and pops. After 5 minutes the engine runs better and you can rev with some popping noise in the engine. Driving the car you feel the engine surging when cruising at 30mpg and does not perform well with popping noise (I don’t think it’s backfiring in the exhaust - sounds more like in the intake area) I did test for vacuum leaks. Pressurized the system and sprayed soapy water everywhere, manifold, injectors, exhaust manifold etc. No indication of a leak. Car has pop off valve.

AAR Test
Half open at 80 deg. With power to the AAR, it closed after about 5 minutes.

CIS Pressure test

1. Installed the pressure gauge between WUR and FD with shut-off valve on the WUR side (edit: originally misspoke and said valve was on FD side)
2. Jumped FP relay terminals #87A & #30.
3. Turn the ignition switch @ ON and start the FP.
4. With the valve closed (FP running) system fuel pressure was 4.8 bar
5. Opened the valve control fuel pressure to engage WUR; pressure would not drop below 4.5 bar. After 4 min. no change in fuel pressure. Turned off FP and after 10 min. pressure slowly dropped to 1.5 bar
6. Triple checked my test equipment and connectors for anything that might constrict the flow of gas blowing 60 psi through hose connectors. Air flowed freely. Also checked gauge accuracy using compressor air (60 psi from my compressor connected to fuel test equipment) and the test equipment gauge read 60 psi
7. Retested twice more, same results; fuel pressure at 4.8 bar would not change much when I opened the valve to the WUR. Same results as above.

Deduced I have some constriction in the lines somewhere.

Constriction Test

1. Connect the CIS pressure gauge between the WUR and FD
2. Disconnected the main return fuel line fitting behind intake runner #3.
3. Connected a temporary plastic hose for the return line from FD to a one liter bottle to collect the recycled fuel during the test.
3. Turned on FP and the bottle filled in less than 10 sec. Fuel pressure almost reached 4.8 bar
4. I tested return main fuel line to fuel tank by blowing air through line, I could easily push remaining gas in line through the tunnel fuel line and then could hear bubbling noise in fuel tank. (as part of restoration fuel tank was pulled and cleaned and new tunnel fuel lines were installed.

I now believe the constriction is at the WUR. Can a WUR get clogged internally?

WUR Bypass Test

WUR screen looks clean. WUR # 0438140045
Test of continuity OHM 27.7
11.5 volts to electrical connector when FP is on.

1. I left the fuel pressure line attached to the FD.
2. I have a lot of fuel line parts so I was able to bypass the WUR and connected other pressure test line to the WUR banjo. Thus the WUR is eliminated from the system completely.
3. Turned on the FP and the gas flowed easily through the system. The Fuel pressure gauge did not move. There does not appear to be an issue with constriction in fuel lines
I believe now believe the constriction may be in the WUR.


Thinking I’m going to send Tony a PM and get his thoughts. I’m not familiar with all that can go wrong with a WUR but it’s my belief that this one has a problem.