So the project jag has another issue…

I am pretty sure I have dwindled it down to the faulty MAF or the fuel pumps. The car starts, runs for a couple seconds, then stops. Smacked the tank and she runs again… pretty sure this is my pumps going out- finally. I am surprised they still work after sitting for 5+- years!

So now I am looking to upgrade pumps preferably to something that has better performance and won’t go bad sitting. I may as well
I’ve read the Bosch 040 is a good option, but I’m uneasy about putting in something that causes too much pressure in the fuel rail. (Or heat in the tank) I have very little knowledge about fuel pumps to begin with, but I do know the XKR has two. Should I get the oem pump and the 040 as the secondary? Has anyone upgraded their pumps and what should I avoid?

 

The original pumps lasted for 23 years, the last five of those spent pickling in slowly deteriorating petrol. I'm not sure what pumps you can buy that will do better than that.

 

^^^^ this !!^^^^^

my original fuel pumps (2002 vintage) are both still going strong. Hoping to keep them happy by daily use

 

While I do not run mine on a daily basis, in order to emulate "Z", every six months,I check / exercise both (especially the secondary) of my 2014 Bosch pumps by pulling relays and jumping each relay socket pins 30 to 78 with a paper clip.(no need to to have ignition on or running a wire to the + battery terminal)
FWIW, at the same time, I also check for 100% WOT / throttle cable stretch.

 

I upgraded the fuel pumps in my 03’ SV8 using Walboro GSS340. I run one in my Grand National for years now and I know other people that use the Walboro GSS340. If you don’t plan on modifying your car, just get Denso fp’s and be done with it. The other thing I did while I was in there was replace the factory plastic Y with a Metaland brass barbed 5/16” Y from Amazon and used Gates 27093 5/16” submersible fuel injection hose. I bought 3 feet of it $$$$. It absolutely must be specifically for submerging in today’s fuel.

 

Your car has the twin pump system? What’s wrong with the OE pumps. They’re good enough I think, unless you’re looking to modify your XKR for a much higher power output?

 

Thanks everyone for the input! Yes, I do plan on modifying the car, but as of current I believe the pumps are failing. It is causing the car to sputter on acceleration, die, ect. I would like to upgrade the pumps as well to support higher pressure, but not too much as to break anything.

 

How much power are you looking to make? Will you be going with a twin screw supercharger upgrade?

 

Upper and lower pulleys, upgraded cooling, exhaust, and I have the Mina intake on it already. Possibly a tune as well.

 

Good luck getting anyone to tune the stock ECU and getting it to stick. You'll be better of getting an aftermarket ECU and tuning with that. Everything else you mentioned will not be enough to necessitate upgraded fuel pumps. However, if you were to swap your supercharger for a Kenne Bell twin screw, that might require more flow. It has been done. Avos has about 700 HP on his car. He stopped making the kit, but as I understand, two other forum members have begun making a kit. It will provide way more horsepower than doing both pulleys ever will.

 

My naive understanding is that the biggest blocker to making more power on the 4.0 XKR, aside from the ECU not being tunable (aftermarket ECU can change that) is the fuel injectors, afaik there aren't great options for replacements that can deliver more fuel. 4.2 has a lot more potential, I recall reading somewhere on these forums.

 

You do not need more fuel, higher fuel pressure or other (bigger) injectors. The supercharger is close to its max even as standard. With upgraded pulleys you get more torque in the midrange but not a lot more horsepower at the top. That because the supercharger starts to make more heat than boost. But it will not lean out even with everything else stock.

 

Take that as a major red flag. Gas does not do well sitting over time. It separates. Everything it touches becomes covered in a tree sap-like sticky gunk. The rest stinks terribly and isn't much like gas anymore. Separately, with that many cycles of condensation and evaporation, chances are the exposed surfaces on the inside of the tank are covered with rust.

You might want to open this up and perform a visual inspection. Then drain whatever fuel/water is left, replace both pumps and the fuel filter. If here is rust, there are treatments available to clean and seal the interior surfaces.

Best of luck, keep us posted.

 

Here is the result of pure gas, not ethanol, that sat for a little over a year:
It corroded the jetting in the two left carbs to the point of uselessness.

 

I don't understand. I've stripped and rebuilt carbs which have sat unused for 10 years or more on many occasions from barn finds etc and I have never seen anything like that in 55 years of spannering. I've always found each of the carbs to be pretty much the same internally, with only slight differences if the bike was stored on its side-stand, so why would two floats be so badly affected whilst the other two look exactly as I have always found them?

Richard

 

You’re just plain lucky

the bike was leaned up against the interior wall of a climate controlled building, no side stand . The two clean carbs were on the high side and all the gas in them drained into the two crapped out carbs.


that’s all I know . I don’t have any answers, only observations that may or may not be useful to others.

I can with certainty say that if the gas is drained out of any vehicle or lawn mower, etc before storage, then these things won’t happen.

otherwise, who knows what will happen ?

Z

PS: I did work on the service side of the motorcycle and vintage restoration industry off and on for 50 years. So I saw a few thousand machines that had suffered greatly under the ownership of people who just didn’t give a damn.