1996 Collector Edition Corvette

[wxo]

Just a quick update. Silvia has blown two Fuel Pump fuses lately. Yesterday, I rigged up an AMP meter to check the draw of the fuel pump. It was 5 amps on a 10 amp fuse. This is intermittent and I have not yet pinned down the circumstances causing it. In the mean time I have a bag of 10amp micro blade fuses coming to allow me to do some road testing. Next, I'm going to study the circuit diagram in the FSM and go from there.

[wxo]

It didn't take too long to diagnose the blowing of fuel pump fuses. On Tuesday I went out to do some testing to see if I could find out what was causing the FP fuse to blow. I put a lot of miles on her and she ran very well. By the way, this was running with the FP pressure set at 44 PSI. I did one quick stop to see if I could reproduce the problem, but the hot start went well, so I thought about heading for home. Instead, I decided to pick up a prescription waiting for me at Walgreens. Prescription in hand I jumped into the car and watched the ammeter as I hit the starter. It was 13 amps and blew the 10amp fuse. So I stuck in a 15amp fuse and tried again. Still 13amps. The fuel pump appeared to be seized up so I called Hagerty Insurance and asked for a ride home for Silvia. This was her third experience coming home on a tow truck.

So I jump on Amazon and order another FP. It arrived next day and I installed it today. It started right away and was pulling about 3/4 the amps of the old one. It runs at about 4.25 amps on average. I've not tested it yet, but I hope to go out tonight to see what happens.

[TireSmoker]

Good diagnosis on the fuel pump draw.

Hagerty sent a guy with a truck and trailer?

-Dave

[wxo]

Yes they did. I was surprised to see him drive up in that rig. However, he was prompt. We waited only about 30 minutes. His equipment was well worn, but it got the job done.

[wxo]

I think this new fuel pump has a problem. I notice that the fuel pressure starts dropping rather quickly right after the engine is shut off. There is a check valve in the fuel pump that should prevent this. I called Delphi tech support and got a guy who actually understood what I was talking about. He said that the engine should start instantly after sitting all night. If not, the pump is defective. I'm going to test it out and send it back to Amazon if it fails.

[wxo]

I've been assessing the problem of losing fuel pressure after the engine is shut off. Over time, it appears that the loss of pressure is slowing down. In other words, the pressure is holding longer than initially. Over night, it goes to zero, but it will start rather quickly in the morning. If I hold the key in the on position a few seconds longer before cranking, it starts instantly. All in all, it appears to start predictably. So, I think this issue is not worth pursuing at this time. I have other fish to fry. I have a very annoying noise that I think is the exhaust in contact with something. It looks like its time to get the jack stands out again and have a look around. I also have a strange clicking when applying the brakes. I think these two issues are next on the agenda...after we go to the beach . Looking past that, I have to figure out how to get the passenger seat all the way back for Fred's visit in June. Currently, the power seats are not moving at all.

[wxo]

First the noise:
This one whipped my butt. I had to remove the underbody X-braces (convertible only) to find the problem. One point on an X-brace was in contact with an exhaust pipe. Over time, it would have worn a hole in the pipe. Good thing I felt/heard it. At a higher level, it was a question of how to correct it. My X-braces are a bit beat up and have some non-factory bends in them due to contact with low ground clearance obstacles in the car's past. The other part of the equation was the exhaust system which was recently re-installed. I decided to start by working to get the exhaust system tucked up as high as possible, so I loosened all the joints and hangers. I then lifted the whole system with my floor jack and tightened all the joints and hangers. I also bought all new stainless nuts to be sure I had proper torque everywhere. Once I was happy with all that, I turned to the underbody braces. I had to fit each one separately. I corrected the bends along the way like this:

This may have been the toughest of all the previous problems Silvia has thrown at me. I took her for a ride this afternoon and the noise appears to have been eliminated. The new fuel pump appears to be working nicely, also.
Next the clicking noise in the front brakes:
This one turned out to be movement in caliper when applying the brakes. The calipers are fastened to its bracket with a pin at the bottom. The top of the caliper hooks onto the caliper bracket and swings on down to be held in place by this pin. I had reused the old pin when I redid the brakes a year or so ago. Thinking the the pin was worn, I ordered some and when they arrived, I found that they were the same diameter as the old pin. Researching further, I learned that my 13" brakes requires a pin with another part number. I found one on Ebay and it is on its way. These appear to be quite scarce. If it fixes the clicking, I'll keep watch for another one to pop up as time goes on.
Next to the seats:
The passenger seat needed to come out if just to clean the carpet underneath. This is where I found the dried up mouse a while back and his remnants have been a source of odor. So I deep cleaned the carpet and went on to find a way to move the seat without using the motor. I was able to disconnect the flexible drive cable for the back and forth motion and use my drill motor to easily move the seat actuator from all the way forward to all the way back. Now Fred can get in and ride along when he comes to visit.

Finally, while looking around under the car before taking it off the jack stands, I spotted an oil leak in front of the engine. Its in the area of the cam chain cover. I saw a drop of oil, but could not see it's origin, so I did the right thing and sprayed it with Brake Clean and decided to keep watch on it.
I have no motivation to dig into that part of the engine unless it turns serious. Right now it is not dripping on the floor so it can wait.

[wxo]

ODO: 103940
I drove Silvia in actual Raleigh traffic this morning and the throttle response at the recommended fuel pressure of 43.5 psi proved to be unsatisfying again, so I started to incrementally bump up the fuel pressure. Each time I added 1 psi, the drivability improved. When I got it running to my satisfaction, it was at 47 psi. The fun meter went up each time I adjusted the regulator.

I took Maverick for a ride this afternoon and he approved of how well it is running. I need some more seat time before I can call this done, but I'm close now. I suspect the failed fuel pump was possibly the reason I had to jack up the pressure to 55 psi in the past. It runs well at a more reasonable pressure now. Also, the new FP now seems to be holding pressure much better when the engine is shut off.

Maverick also worked with me to adjust the drivers door. It was not easy, but we got it closing with a satisfying click and the gaps look very good now.
Maybe when Fred comes to visit, we can work on the air conditioning. Summer temperatures have arrived in Raleigh now.

[wxo]

ODO: 103989
On Tuesday, I took Silvia out to stretch her legs. On the way, I noticed that a "Check Gauges" message had appeared on the dash. This is a warning that the PCM puts out to tell the driver that it had detected an issue on one of the gauges. I looked over them quickly and could notice noting amiss, so I went on. I few minutes later the warning light went off and stayed off. What the ...??
When I got home, I looked over the gauges and still couldn't see anything wrong. The next day, yesterday, I decided to drive Silva to my doctor's appointment. Before leaving, I noticed that the gas gauge was showing less fuel than I had expected to have. It was still a bit less than half a tank, so I went on. On the way, the "Reserve" light lit up and the gauge was showing near empty. What the ...?? I was near a gas station, so just in case, I pulled in and filled her up. What the ...? The pump had clicked off at 6 gallons!! It's a 20 gallon tank. Since I had my UltraGauge on board, I reset it to start managing the fuel supply and felt somewhat relieved. I'll put this issue on the back burner for now as long as the UltraGauge works as a good backup. This fuel level and fuel pump assembly from Delphi is the same one that gave me the recent bad fuel pump, so now I'm suspicious. Oh well, just one more thing to add to the list.

[wxo]

ODO: 104016
I took Silvia out to pick up dinner this evening. She was running perfectly with the fuel pressure set at 46 psi. On the way back she just quit. I took a quick peek at the fuel pressure while on the side of the road and it was ZERO when I turned the key on. Could it be another failure of a brand new Delphi fuel pump??? If it is, I need to choose a different brand. A BMW mechanic stopped to see if I needed any help along the road. We started talking and he reacted quite negatively when I mentioned that this was a Delphi pump. He suggested Walbro, so Walbro it will be (probably).
This is the fourth rollback ride for Silvia since we met.

[TireSmoker]

All my EFI stuff has Walbro pumps -- they're good stuff.

-Dave

[wxo]

I did a bit of diagnosis today. I put an ammeter on the FP fuse and turned on the ignition. The meter went to 2.9 amps and then to zero in a few seconds. The FP gauge quickly registered 5 psi, then zero. Then, to check for some sort of blockage in the fuel system, I removed the output fuel hose from the pump and added a short section of hose to a plastic jug. When I turned on the ignition, there was a short spurt of gas and it stopped. I would guess about a cup of fuel came out. The fact that it pumps fuel at all makes me wonder if this problem is really the pump. Any thoughts or ideas out there?

I have a Walbro pump ready to order from summit, but I don't have 100% confidence that the pump is the problem.

[wxo]

Maverick called and urged me to jumper the pump directly to the battery, so I did. I saw similar symptoms. The pump puts out only about 5 psi. The order is in for the Walbro.

[wxo]

We pulled out the fuel sending assembly to replace the fuel pump and noticed a blown out hose that attaches the fuel pump to the rest of the fuel system. What a surprise! This explains the 5 psi on the fuel pressure gauge. Too bad I already bad-mouthed the Delphi fuel pump. It was doing it's best to pump fuel through that hole in the hose. The hose was part of the kit that is included in the pump installation kit from Delphi, so Delphi was indirectly at fault for this problem. I found a piece of hose in my hose drawer and a couple of clamps and repaired the connection.

When we pulled out the fuel sending unit assembly we also saw the reason for the fuel gauge malfunction. The float arm was missing!! Obviously it was floating somewhere in the tank, but we couldn't see it. So I took a long piece of coat hanger wire and went fishing. As I did this, the float came floating by the access hole as I disturbed the gas in the tank. We fished it out and saw that it had just come undone from the fuel sending unit. It just clips in like carb linkage. To prevent this from happening again, Fred suggest using a very thin zip tie to fasten it more securely. This worked great.

Next we reinstalled the whole unit, adjusted the fuel pressure and went for a test drive. It ran well, but, alas, it still had the cough/bog issue but the fuel gauge is registering correctly. Back at the garage, we took a look at the fuel pressure gauge and it looked good, but I noticed that the vacuum was not attached to the FP regulator. My BAD! This fixed, we went out again to see the results. Problem solved! It now ran like it should (again). Next, I wanted to set the FP back to stock to see how it would run there. It is running well and happy for now (with the Delphi FP).

[TireSmoker]

I think Fred has the distinction of riding in all the C4s of Tiresmoke!