Classic/Antique Car Repair: 1980 Rolls Royce Shadow 2 carburrated, facet pump, fuel mixture

Question
QUESTION: My fuel pump failed.They don't make Pierburg anymore so it was replaced by a purolator facet pump.After going through 3rd gear the car would flatten out and feel like it is on four cylinders.If you put it in nutral you can rev the engine with power.Put it in gear and it doggs down on acceleration. I again replaced the fuel pump,checked the filter and replaced the carburators filters.Same problem.If you put on the air conditioning it's worse.Slow acceceration with the peddle allows acceleration some times.
Could it be fuel mixture?


ANSWER: Hi George:
Please describe to me how you start your Silver Shadow. Did you press the accelerator slightly to start her, or do you hold it to the floor or do you pump the accelerator? RR's will flood easily and it can take a while to burn off excess fuel. The best way to fixed this problem is to take her on the highway and blow her out real good at 70 mph. But never press the gas more than an inch when starting her.

When started, let her warm up for about 2-3 minutes, then tap the gas quickly to release the automatic choke. She should idle down and you should be able to drive her normally at that point.

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QUESTION: I put the key in and turn on the ignition without starting.I hear the fuel pump and wait a minute.I press the accelerator once quickly to the floor and can see with the hood up that the choke rod drops to 6 o'clock.The car idols high as the rear rises.After 2-3 minutes I press the peddle to the floor quickly and release it and the car idles smoothly.No smell of raw gas or anything.I let the car run for 5 minutes and then drive it.After 3rd gear and just above 40 it feels like it's a four cylender.Take my foot off the gas and repress and accelerate for a bit and then it dunks again.Now I have noticed that when the heat gage is right at the bottom of the white heat level mark and after driving for twenty minutes with the air off all of sudden the car accelerates fine like nothing is wrong.Then I slowed down ,made a u turn ,put the air on and accelerated.It started dunking again.It definitly is a loss of fuel to the system, but take it out of gear and hit the gas peddle and there is plenty of power.Put it back in gear and it loses power.If you floor it it just stays as if it is firing on four cylenders.No backfiring or any thing esle,just loss of power.


Thanks george

ANSWER: You know, this could be the carbs. Do you add oil to the carbs each time you change the engine oil? Maybe the fuel pump is fine, but the hydraulic carbs are not pumping fast enough. Also, if the carbs have never been rebuilt, it could be time. You have to fill each carb cylinder with oil at each oil change. The carb take about 2-3 ounces of standard 20/50 motor oil. Are you familiar with the procedure to do this?

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QUESTION: Yes that has been done.The history is I got the car and it drove beautiful,no leaks,no nothing wrong,then one day i topped the rear brake fluid unit with the wrong fluid/I called the rolls dealor and he asked me if I had started the car yet and i said yes, so he said just drive it in.I did and left it with him and when i got it back I started to have all the problems heretofore mentioned.My brake lights came on slowly for pressure 1 & 2, my accumulator started to leak and so on and so on.I had the pump replaced and then came the dunking and since I had the O ring in the driver side accumulator replaced and the accumulators re charged and there was no leak in the diaphrams so the non rolls machanic said someone had simply evacuated the accumulors to cause the lights to come on.It took him a few minutes to take off the cover plates and then recharge the accumulators.He showed me what the diaphrams looked like and they are rubber but you couldn't push an ice pick through they are so sturdy and that's why with no leak into the brake fluid resovoir it was obvious what was done since the guy that did it wanted 1700.00 to rebuild the accumulators when the problem started.Why would the carbs work fine until 3rd gear and reve fine when out of gear.Does load cause more stress on the pump or carbs? What other ajustable units involved with fuel could have been tampered with? Theres a check valve in the book but could that cause the problem.It does feel that maybe only one side of the engine has power when you accelerate.But why would it go away for 30 minutes and then come back?

thanks
george

could it be water settling in the tank between drives and then I don't drive it enough to keep it from happening?

Answer
Hi George:
Sorry it took so long to get back to you, but your problem is a tricky one. I have one question for you...When you experience the problem you described, is there anyone else in the car with you? I have discovered a problem that is weight-related when their are passengers in the back seat. However, your problem maybe more severe and occur with just you in the car. Check to make sure your automatic leveling system is working and that the tires are inflated to 28psi front and 32psi rear.