choob Posted March 25, 2017 Share Posted March 25, 2017 Had a problem crop up today on the RRC. It's got a 3.5 carb engine. After driving WOT, e.g. to overtake, the engine started hesitating when driving more slowly, reluctant to rev and needed the revs kept up or it would threaten to stall. The problem goes away after a few minutes but comes back if I drive at WOT. I dunno how carbs work, any help would be great. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 25, 2017 Share Posted March 25, 2017 Sounds like fuel starvation to me... Dead fuel pump or kinked/blocked fuel supply lines, filter, carb float needle etc... Quote Link to comment Share on other sites More sharing options...
Snagger Posted March 26, 2017 Share Posted March 26, 2017 A partial blockage of the fuel tank breather may cause these problems - while the fuel flow is greater at full throttle, so is the suction, but with the tank vacuum building up and the carb choke chamber vacuum reduced at partial throttle, the fuel flow may be stagnating. Worth checking the fuel pump too. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 27, 2017 Share Posted March 27, 2017 Surely #1 suspect for fuel starvation on an old RR would be the fuel filter? Also the SU's need oil topping up every so often. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 27, 2017 Share Posted March 27, 2017 Well yes, I thought for some reason I had included that in my list above, must be going senile Quote Link to comment Share on other sites More sharing options...
choob Posted March 30, 2017 Author Share Posted March 30, 2017 Thanks for the replies. The breather is ok, and I changed the fuel filter today. Let's hope that helps. Thanks again, I will report back. Quote Link to comment Share on other sites More sharing options...
Davo Posted March 31, 2017 Share Posted March 31, 2017 It should have Strombergs, not SUs, but they could have been changed. In any case, unless you actually know the carburettors have been rebuilt, then you should do that, because once they age the engine will never run right. Other than that, you have to go through the usual service items as mentioned above, and definitely include the ignition system as well. Once everything is up to standard, then either you won't have any more problems or, if you do, then you can start troubleshooting in a methodical way instead of just poking away at the thing and hoping for the best. Quote Link to comment Share on other sites More sharing options...
choob Posted April 1, 2017 Author Share Posted April 1, 2017 It does have Strombergs, not SU. Ignition seemed ok, was hoping it wasn't the pump as previous car (3.9) had in tank pump but this has an external pump so if that dies shouldn't be too much of a pain to fix. I don't know how to rebuild carbs, and I sure don't trust anyone here (east africa) to do it except maybe a couple of old rally drivers who used to race them. Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted April 1, 2017 Share Posted April 1, 2017 On 3/25/2017 at 7:19 PM, choob said: Had a problem crop up today on the RRC. It's got a 3.5 carb engine. After driving WOT, e.g. to overtake, the engine started hesitating when driving more slowly, reluctant to rev and needed the revs kept up or it would threaten to stall. The problem goes away after a few minutes but comes back if I drive at WOT. I dunno how carbs work, any help would be great. What does WOT stand for ??? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 1, 2017 Share Posted April 1, 2017 Wide Open Throttle The way I rebuild carbs is to un-bolt the inlet manifold complete, sell it to some luddite who still likes carbs, and then bolt on the EFI inlet manifold and a Megasquirt kit. 1 Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted April 2, 2017 Share Posted April 2, 2017 16 hours ago, FridgeFreezer said: Wide Open Throttle The way I rebuild carbs is to un-bolt the inlet manifold complete, sell it to some luddite who still likes carbs, and then bolt on the EFI inlet manifold and a Megasquirt kit. Quote Link to comment Share on other sites More sharing options...
Davo Posted April 2, 2017 Share Posted April 2, 2017 17 hours ago, FridgeFreezer said: Wide Open Throttle The way I rebuild carbs is to un-bolt the inlet manifold complete, sell it to some luddite who still likes carbs, and then bolt on the EFI inlet manifold and a Megasquirt kit. Oh dear God . . . Quote Link to comment Share on other sites More sharing options...
Davo Posted April 2, 2017 Share Posted April 2, 2017 On 4/1/2017 at 7:12 PM, choob said: It does have Strombergs, not SU. Ignition seemed ok, was hoping it wasn't the pump as previous car (3.9) had in tank pump but this has an external pump so if that dies shouldn't be too much of a pain to fix. I don't know how to rebuild carbs, and I sure don't trust anyone here (east africa) to do it except maybe a couple of old rally drivers who used to race them. Ooooh, East Africa, I follow you now. These carburettors are easy to rebuild, especially if you've got the internet. There's not much to them at all, kits are easy to get, and you just have to be methodical. If the throttle spindles are really loose in the bodies then you would need someone to help with that. Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted April 2, 2017 Share Posted April 2, 2017 23 hours ago, FridgeFreezer said: Wide Open Throttle The way I rebuild carbs is to un-bolt the inlet manifold complete, sell it to some luddite who still likes carbs, and then bolt on the EFI inlet manifold and a Megasquirt kit. 5 hours ago, Davo said: Oh dear God . . . Bloody kids eh 1 Quote Link to comment Share on other sites More sharing options...
choob Posted April 6, 2017 Author Share Posted April 6, 2017 It seems ok since I changed the fuel filter...although the oil pressure sensor started leaking today. My mechanic says 'see you next week' everytime I go there >.> Quote Link to comment Share on other sites More sharing options...
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