I will do, but it won’t be for a while yet.
Could no alternator output be the reason for any of my fueling issues? Or would it be entirely unrelated?
Could no alternator output be the reason for any of my fueling issues? Or would it be entirely unrelated?
ukadamwest
Well-Known Member
I doubt it with carbs, however if the pump is not getting enough voltage it could be running slow?
have you pulled the plugs to see how they look ? that will give you an indication of how the mixture in the cylinders is. too weak, too rich, etc ?
No not yet. I only took delivery of it at 4 pm today so haven’t had much time.
I know the chap who had it before me relatively recently replaced all 8 of the plugs though. If I take one out and have a look at the ends, what am I looking for? Black/soot/ carbon build up?
Brill, thanks. Will pop some out tomorrow and have a look.
If I need to get some replacement, are there better brands to go for? Just to double check something, the bloke who sold it to me said it was a bored, polish and ported 4.0 litre, but all I’ve seen online is that the 4.0 has EFI, which mine most definitely does not. So, do I have a bored 3.5, a bored 3.9 or what, and thus, which spark plugs should I be getting?!
You probably have either a bored 3.5 or a 3.9 with a 3.5 intake system. The correct plug from a known brand, like NGK, Champion or Bosch will all do the trick. The NGK should be BP5HS, I think, but double check before buying.
Now, to your idle issue and lack of grunt: I hate to point out the bleeding obvious, but do you know there's fuel in the tank? I'm asking because you stated that very question yourself, and it seems it has yet to be answered. Also, the fact that it ran just fine before you bought it, points to something simple like that. Your fuel pump should definitely slow down once the carbs are full, so you're either low on fuel, have a faulty regulator or a blockage. If your carbs weren't shutting off when the chambers are full, I wouldn't expect the engine to run at all - it would be badly flooded. Your description of the small trickle of fuel you get when you pull the hose off, again points to low fuel or blockage. If the car has seen very little or no use, driving it may have upset sediments in the tank which have now clogged your filter. Advice: Make sure there's fuel in the tank. If there is, find your fuel pump, pull the hose off it and switch on ignition (catch the fuel in a container). Is the flow any better at this point? If it is, work your way through the system and find your blockage. If it's not, pull your fuel pump and test it on the bench. If it's no better there, find a replacement.
Good luck!
Now, to your idle issue and lack of grunt: I hate to point out the bleeding obvious, but do you know there's fuel in the tank? I'm asking because you stated that very question yourself, and it seems it has yet to be answered. Also, the fact that it ran just fine before you bought it, points to something simple like that. Your fuel pump should definitely slow down once the carbs are full, so you're either low on fuel, have a faulty regulator or a blockage. If your carbs weren't shutting off when the chambers are full, I wouldn't expect the engine to run at all - it would be badly flooded. Your description of the small trickle of fuel you get when you pull the hose off, again points to low fuel or blockage. If the car has seen very little or no use, driving it may have upset sediments in the tank which have now clogged your filter. Advice: Make sure there's fuel in the tank. If there is, find your fuel pump, pull the hose off it and switch on ignition (catch the fuel in a container). Is the flow any better at this point? If it is, work your way through the system and find your blockage. If it's not, pull your fuel pump and test it on the bench. If it's no better there, find a replacement.
Good luck!
tomcat59alan
Well-Known Member
Check to see If you adjust the timing with or without the vacuum connected. If without the disconnect the red pipe that runs from between the carbs yo the distributor vacuum advance unit in your photo and blank it off with a bolt otherwise the engine will run weak. Reconnect then you've adjusted the timing.
Last edited:
tomcat59alan
Well-Known Member
Have you photographed the pump yet? Some have a filter which may need cleaning especially if the fuel level has been run low as all the crap will have been sucked out of the bottom of the tank
ukadamwest
Well-Known Member
well done..
yes disconnect the vac line... and don't forget to reattach it afterwards
tomcat59alan
Well-Known Member
Got new alternator this morning. Apart from a bright red light on the dash, every thing seems the same!
I’ve disconnected the fuel pump, and cleaned everything, can breath relatively easily along all pipes etc. Not sure I have a filter as it’s a bit of a home made system I think!
Have discovered that if I turn the key and leave the pump pumping for 30 seconds or so and then start the engine, it runs absolutely fine, but then if you try and give it some grunt, it dies and just splutters out. Sounds like it’s not quite firing on all cylinders when it does that - literally.
It can quite happily stick a idle for 2/3 minutes and then all of a sudden will just die and stop. Can still hear the curl pump running though. HVe attached a photo of fuel pump also at the top because my utterly **** phone won’t let me put one at the end!!
Any ideas?!
The flow seems sufficient, although it's pathetic compared to a modern pump. Have you tried putting your finger over the end of the hose to see if it generates any pressure? Have you got the same sort of flow in the engine bay, or do you loose steam on the way there?
The red light on your dash is the charge light. It should come on when you switch ignition on and then extinguish itself a few seconds after the engine is started. Does it?
The red light on your dash is the charge light. It should come on when you switch ignition on and then extinguish itself a few seconds after the engine is started. Does it?
Flow seems ok in the engine bay: see video below!
Tried folding the fuel pump tube that feeds the filter ( to presumably create a “primed” system) and the pump keeps pumping at the same rate. Would a better fuel pump be advised? It’s a non standRd fuel tank so I think I I’d need something made for any vehicle, not RR specific if that makes sense.
Yes, red light goes off, but flickers on again when engine is spluttering and struggling.
Tried folding the fuel pump tube that feeds the filter ( to presumably create a “primed” system) and the pump keeps pumping at the same rate. Would a better fuel pump be advised? It’s a non standRd fuel tank so I think I I’d need something made for any vehicle, not RR specific if that makes sense.
Yes, red light goes off, but flickers on again when engine is spluttering and struggling.
Sounds a little odd, that your pump doesn't change rate when pumping against a blocked line - it may be leaking pressure back to the intake. You could install a pressure gauge directly before the carbs, to see that your pump and regulator are actually maintaining 3-5psi of fuel pressure. I've never worked on a car with SU's, so I'm not sure how the setup is, but if the sequence is tank-pump-filter-carbs-regulator-tank, you can use any fuel pump without worrying about excessive pressure. If, however, you have tank-pump-filter-regulator-carbs, i.e. that excessive fuel isn't routed back to the tank through the regulator, you probably need a fuel pump with limited pressure output. I know brand new SU fuel pumps, specifically made to feed their carburettors are available, but at a price. An inline pressure gauge is cheap, easy to fit and a good thing to have in any case. It's as good a place to start as any.
brianp38dse
Well-Known Member
The fuel pump you have is a facet or if very old bendix and depending on which model will do up to 8 psi and 36 gallons per hour so should be well up to the job as I use them on rally cars with twin side draughts
You have tank pump fillet regulator carb set up, check to see if you have power to pump if no check for fuse if yes pump gone and you can get one the same on fleebay.
You have tank pump fillet regulator carb set up, check to see if you have power to pump if no check for fuse if yes pump gone and you can get one the same on fleebay.
Last edited:
Right, update!
In answer to question about, no, I don’t think my tank has a return line.
Disassembled fuel pump and plugged it back in, and it works, but have ordered a new one anyway.
Managed to do a bit of troubl3shooting today - wondered if the fuel filter might be the issue so I wired the pump directly to the carb input and it worked like a dream - no issues what so ever. So, I thought, I’ll make it like this permanently so keeping the pump in the engine bay etc and I found an old inline filter which I’m currently using.
However, it now appears that the pump is pumping, but nothing is coming out. Does having air in the line matter, and would the pump “pull” the air out of the line...? If not, how would I go about removing the air from the line as I can’t seem to think how to do it? I’ll stick the new pump on tomorrow which is exactly the same as old pump, but just not sure if th same thing will happen? Does the whole fuel system/line need to be a vacuum or effectively, free of air?
Cheers for all the help so far - I feel like we’re getting there...slowly!
brianp38dse
Well-Known Member
With the new pump it should not need priming and you will probably have to keep running the filter King regulator or the cabs will over fill and leak fuel everywhere.
