I purchased a Jag XKE 2+2 series last year. Last month I noticed a carb leak. I replaced the float and needle valve. The rubber diaphragm is in good condition. Here is what’s happening,
I turn the key and the fuel pump starts ticking. It doesn’t stop and the rear carb starts leaking fuel.
I am guessing the issue is with the fuel pump?
What are the reasons for this? Whats the solution?
Thank you!
Sometimes the floats stick open. Try tapping the carb with a rubber hammer and if you’re lucky it will close. If not you’ll need to take the carb apart , clean it , check for debris and reassemble.
Marco
From where is the fuel coming?
Firstly is it the overflow tube from the top of the rear float bowl that is gushing fuel?
If Yes, then either the float is defective and full of fuel and not floating (not likely) or the needle valve has dirt in it and is not closing. It also may be that the when you screwed the needle valve seat in, that you did not use a sealing washer. By the way, when I put a new needle valve in (and I assume you replaced needle and seat), I put some thread sealant on the threads of the needle valve seat before I thread it in.
If it is coming from the bottom of the carb where the jet is, then it is the diaphragm.
Did you check the float level height setting as per the manual?
Dennis
69 OTS
Misky;
First of all welcome to the site. There are many good people here and all are willing to help.
To give you the best chance of getting the right answer we need to know the year of the car, the engine and the carb set up (SU’s or Z-S’s) .
Regards, Joel.
Not a problem with the fuel pump, definitely within the carb float bowl, either as stated the float has a hole in it and is floooded o the needle valve is stuck. There is one other thing that can happen (well it did on my S11 XJ6) I had the car on ramps and the rear float bowl must have been empty as when I turned the ignition on the pump did not stop, on investigating the rear carb was flooding, tapped the side of the bowl and it freed up the float. It had managed to rack over and stay in th bottom of the bowl.
I had this same problem a few weeks ago, so I’ll pass on the advice I received.
If your float level is set too high, fuel will rise up through the jet and dump out the front of the carburetor.
If you don’t have notched washers on your overflow banjo, your bowl will be sealed, and the resulting pressure will force fuel past your jet.
If fuel is dumping out the overflow tube, either your needle is stuck, or your float is sunk… it happened to me.
Thank you gentlemen (Mark, Karl, Dennis, Joel and Robin) for responding so promptly to my query! Very kind of you all! I’m sorry I did not provide the details of my car in my haste Joel. It is a 1969 series II 2+2 and the carburetors are SU 175CD. I have cleaned the rear carb and replaced the float but did not double check it for height Dennis (original one was indeed defective and had absorbed fuel). The rubber diaphragm is in good condition too. I did install the needle valve with the washer (as before: but did not put any thread sealant on it). The carb is leaking from top of the overflow tube (photo attached). I also noticed that my fuel metering needle/jet needle is a bit old and I’m not being able to release it even though I’ve got the grub screw out. Do I need a special tool for this or is there a secret to it? Once I’ve changed it I’ll try to give it another go and see if the fuel pump ticking is gone along with the carb leak. In the meantime thank you all for your help and goodwill!
Joel missed the thread title says SU but you missed the carbs are not SU but Strombergs.
When you have sorted the leak, look up how to configure the secondary throttles very easily to markedly enhance pick-up. There is a thread called something like ‘Five minute Strangleberg fix” or “Crespin mod” where somebody supplied annotated photos.
Apologies! I meant Stromberg 175cd carburetors. Thank you for the tip on how to enhance pick up Peter. I’ll try and attempt that as soon as I fix this leak. Thank you.
I had a heck of a struggle getting the needles out of the pistons on my '68 Strombergs. It really came down to brute force. Soak the needle base with a penetrating oil for a while first, and be prepared to mangle the old needle. Contact Joe Curto for the correct replacement needles (I’d do both as if one is in bad shape, the other is likely the same). Be very careful not to distort or damage the piston. This is what I ended up doing…
Thanks Doug! I was’nt sure if I had to pull them straight out or use a special device from the other end. I suppose vice grips and force will have to be used. I tried penetrating oil last night and tugged a bit but they refused to budge. Appreciate your tip on Joe Curto. I had ordered a needle via SNG Barratt a month or so ago but I’ll keep the gentleman in mind for the future!
Thanks Joel for your gracious welcome. Amazed to find this source. I have a 1969 Jaguar XKE series II 2+2 with Stromberg 175 CD-2 carbs.
Thank you Dennis for narrowing down the problem. The leak is coming from the top. Please see the photo I’ve posted where I’m pointing to it. Also, the previous needle valve that was installed had a single washer and no filter, however, the new one three washers and a filter. I’ve been assured this needle valve is for my car by SNG Barratt. Do I have to use all 3 washers or just a single one. I’m a novice at this I’m afraid!
I dont know how many washers are needed as I am not that familar with strombergs
I am sure someone will reply to that
But I do suggest you use thread sealan/threadlock if you take it apart again.
Wait 24 hours after reassembling for the thread sealant to harden
Dennis
If you told SNG Barratt that you had SUs, as you did this forum, you may well have the wrong parts. I don’t recall ever seeing a filter in the Stromberg carbs, but SUs have them.
-David
But did you set the float height?? You CANNOT change the valve and expect the float height to remain correctly set.
Which positively indicates the gloat valve is NOT closing properly. This can be because of a bad valve, or incorrect float height adjustment, or too-high fuel pressure.
I hope you’re not expecting changing the needle to have ANY effect whatsoever on the leak. It will not.
Regards,
Ray L.
Hi David, I’m sorry I said SU by mistake. I meant Stromberg. No SNG made sure to double check my make and model before sending the part. Photo attached from their website.
Link to their description:
https://www.sngbarratt.com/us/#!/English/parts/95a66d74-95d1-4649-9cf5-18d756ae0ca1
Will do! Thanks Dennis.
Good points Ray. I’ll double check the float height as per the manual. That is what Dennis had also mentioned. I do admit I did not do that and that is probably what is causing the issue. Regarding the needle, I just thought I’d change it as it looked old and a bit gunky.