WUR issue

[howard freeman]

This connector

[howard freeman]

another angle

[boyt911sc]

Originally Posted by howard freeman

You didn't read the post correctly! I said 12 pin connector,"not" the 14 pin at the regulator panel.
Howard

Howard,

I did misread your post and the 12-pin connector from the ECU is not the 14-pin I mistakenly identified.

Tony

[schumicat]

Using a better quality gauge set, I confirmed the system pressure is in fact way too high (around 90+ psi). Tony suggested this could be a blocked return line. How do I check that? Where does it run? Thanks much.

[boyt911sc]

Originally Posted by schumicat

Using a better quality gauge set, I confirmed the system pressure is in fact way too high (around 90+ psi). Tony suggested this could be a blocked return line. How do I check that? Where does it run? Thanks much.

schumicat,

Before you go chasing the problem, familiarize yourself about the fuel line system of your car. The first part is the delivery and the other is the return. If the control and system fuel pressures are identical (which is most likely in this case), then the restriction is some where along the return line.

Could you check and confirm that the return fuel line is connected to the correct fitting? If you inadvertently connect the return line to brake vacuum line ('81-'83) which I have seen happened before, you'll have this 90 psi. plus fuel pressure. If this is not the case, then the restriction is between the FD and gas tank. Keep us posted.

I'll prepare a step by step procedure to locate the restriction for you. Do some inspection first. Thanks.

Tony

[schumicat]

I don't think the return fuel line is connected to the brake line. I don't think I disconnected the brake line at any time to drop the drivetrain. I just looked to see if any fuel lines were twisted or something and they looked ok. But it looks like there are couple of lines in back of FD which run behind the intake boot and impossible to see. I'd appreciate troubleshooting procedures. Thanks

[howard freeman]

How in the world did someone get the return line connected to the brake booster line?
Howard

[boyt911sc]

Originally Posted by howard freeman

How in the world did someone get the return line connected to the brake booster line?
Howard

Howard,

That's how I found it when someone installed his '78 SC engine in an '83 chassis . I got a call from a local Pelicanite about his cold starting problem. Came over to see what's going on with his start-up after installing the engine to a new chassis (track car).

When I first arrived at the scene, everything seemed to look normal and the owner mentioned his difficulties getting the engine to run. I hooked up the pressure gauge and the fuel pressures (control and system) were both too high at 90 psi plus. This could only meant that the return fuel flow was restricted somewhere!!!!! The question was where?

To prove my suspicion, I isolated the car's return line and installed a separate delivery system shown in the picture below. After connecting the improvised set-up, the pressure gauge registered an 18 psi control fuel pressure and a system of 72 psi. Turn the ignition switch and the engine turned and stalled. Try the second time and it roared to life!!!!



The big question at that time was, why the engine ran using the improvised delivery and return system but failed with the car's fuel line system. The answer was simple. There was an anomaly in the car's fuel line system. And I had no answer at that time. But one thing was demonstrated that the engine was working with the improvised fuel line system.

Description of the McGuiver system:
1. Delivery line system: A plastic fuel tank connected to a FP delivers fuel to FA to fuel filter to FD.
2. Return line system: The return line from FD is diverted back to the plastic tank. Thus eliminating the use of the car's return line.

So for the skeptical that this could or would never happen actually happened and I didn't do it. Don't kill the messenger. This was the guy you should question not me!!!!



Problem identified: The fuel return line from the FD was inadvertently connected to the brake booster vacuum line!!!! End of story.

Tony

[Paulporsche]

Even w/ these old cars you see something new every day!

[howard freeman]

I thought I had seen it all,but here again is another new one. Where did they mix them up ?? at the tunnel connections??
Howard

[schumicat]

update.

Tony said the fuel return line to the tank must be blocked to cause the system pressure to be so high. I removed the return line (between the fuel distributor and the chassis) and saw that it was clogged up with what appeared to be rust/grime/dirt. See photo attached. This line had to be disconnected to drop the engine, which stayed out of the car for months. The return line is low pressure, so the fuel could not break through this blockage (which seemed to be limited to the fitting, which was sitting exposed attached to the engine while it was out. In the future I will cover the removed lines. I cleared the line with a bike brake cable. Hopefully can reinstall soon and get car running. Thanks to Tony for his troubleshooting help!

I also figured out what was wrong with my Harbor Freight fuel pressure test kit. Some of the shraeder valves in the quick connect fittings were screwed in too far, so they would not open when coupled because they didn't stick out far enough. They are exactly the same as tire valve cores. I had a valve core tool I used to unscrew them a little and now there is good flow when coupled. so now I have two fuel pressure test kits (bought a different kit before figuring this out).