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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 573 |
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Your first message sounds familiar to me.
For starters, replace the fuel filter, preferrably with a large one. Then inspect the contents of the old filter. If it's empty (no collected debris), then I'm barking up the wrong tree. Ignore me. If there's a lot of debris, enough to inhibit flow through the filter, and if the engine now runs better with the new filter installed, then we're on the right track.
If there's a lot of debris present, much of it rust colored, then the fuel tank is rusty/ crusty inside. Continuing to replace the fuel filter with large ones will help put-off the inevitable, but the real fix is to remove the tank and either have it cleaned out and coated inside, or replace it.
Also, remove the carbs' top covers and inspect the float bowls for flakes rust-dust. "Any" is a bad sign, it doesn't have to be a significant build up. If there flakes present, then remove the carbs for a good cleaning. If crud is in the bowl, then it's also in the rest of the carb where you can't see it.
*~*~*~*
I once had a 'strong' 907/ Dellortos suddenly start running like it had a built in speed limiter. When cruising on the freeway, it would run normally at speeds below 63 mph. At 63+, the engine would begin to lose power. The more I stepped on the throttle pedal, the worse it got. Once started down that path, lifting off/ slowing down would not help. The engine would slow to the point that I had no choice but to pull over to the side of the road. Given a few seconds to catch it's breath, the engine would soon start to 'pick-up' and run normally again. It would accelerate back out into traffic, it could cruise at 60 mph for miles without a problem, until the speed touched 63 mph again. Repeat, repeat.
Removing the carb covers revealed rust dust. Checked the filter, and it was full of rust dust. The fuel lines, Flowlok valve and aftermarket inline fuel pressure regulator all had rust dust in them. When I opened the aftermarket fuel pressure regulator, it was packed so full of rust mud that it made a perfect impression of the inside of the housing. It was like opening a mold. The pump was only able to push enough fuel through all that mess to support 63 mph. Period, no debate.
I did a comprehensive clean-out by opening/ cleaning/ re-assembling the carbs, SU fuel pump, Flowlok valve and pressure regulator, plus replacing all fuel lines. Two large (fuel injection size) fuel filters were installed, one at the outlet of each fuel tank (Esprit has two tanks) and prior to the SU fuel pump, and a third smaller filter as close to the carb inlets as possible. That band-aide fix, plus regularly checking and replacing the filters, worked for the short term and the car's top end performance was restored. However, the real fix required fixing the tanks. I'm guessing that's what you're facing now.
Regards,
Tim Engel
Last edited on 11-16-2018 05:58 pm by Esprit2