Zongshen 625cc
 

Hi, first off I want to say this is the first time I’ve had a golf cart! I purchased a 2004 EZGO TXT that has the Zongshen 625cc engine it from Vegas carts. When I give it gas it does not idle up or go any faster. It has a fuel pump on it with three hoses, 1 from fuel tank and one going to carb, and the 3rd hose looks like it’s going into engine and when cart is running fuel flows a little at a time into this hose to motor! The oil is way full and looks grayish. Weird smell I’m not sure if it’s gas or what! Please help! Thanks Y’all.

Re: Zongshen 625cc
 

That line that goes to the engine is actually the "pulse" line and it is getting vaccum from the action of the piston in the cylinder from below in the crank case. This pulse activates the pump, pulling fuel from the tank, and pushing it to the carb. There is a rubber membrane in the fuel pump that separates the chambers, and it is likely that this membrane has failed. Get a new fuel pump or replace the membrane. Also, you will need to change your oil, as is sounds like you have gas in the oil.

Re: Zongshen 625cc
 

Another way around all these pulse pump issues is the Holley Mighty Mite 12-426 electric pump. I was using the B&S vanguard pump on both carts but in both cases it eventually failed like all the other pumps I tried. The sled powered cart it lasted only 1 season. Maybe due to having to pump the 50/1 fuel mix along with the 6500 rpm range of the sled engine. The clone powered cart it lasted 3 seasons again possible due to the 5000 + rpms of the VC 460 or modern gas. I am sure others will have their take on this issue but this is my latest idea on fuel pumps for engine swapped carts. P.S. I am using a 625 carb on my VC 460 and needed a return with the Holley pump.

Re: Zongshen 625cc
 

Using stock pump on my G9 to my clone. So its a 1992 pump and I have never touched it, works great. When I get over 5K rpm it can get a bit of oil in the pulse line which is a common issue at high rpm. I plan to change the way its hooked up and see if I can avoid that, but I don't run it that fast normally.

Re: Zongshen 625cc
 

First before anything else, change the oil! Gas contaminated oil will spell disaster for these engines. Refill with a quality brand oil, 10w-30. Since this engine takes just over a quart, no reason not to spend the extra couple bucks on synthetic.

There should be no fuel present in the line that runs to the engine crankcase. If there is, the pump is done and needs replacement. If there is oil in this line, the pump has probably been contaminated and needs replacement. Start with a replacement pump, this one works nicely on my 625:

https://www.amazon.com/Walbro-FPC-1-...s%2C186&sr=8-5

Ensure all lines are run properly, the pump has arrows and letters for the different lines. Arrow pointing towards the pump is the fuel inlet from tank. Arrow pointing away from the pump is the fuel outlet to the carb. P stands for pulse and is the line that connects to your engine crankcase.

When that is all hooked up correctly, try running the engine. Some carb tuning will be necessary, as it is very unlikely to run well out of the box. First step is to get idle set, and a tachometer is highly recommended. Idle needs to be low enough to allow the cart to shift but high enough to keep from stalling. Once the idle is set, then you can work on carb adjustment through the rpm range. Again, an adjustable main jet is highly recommended for this step. It will make your life much easier. Try this one from NR racing:

http://www.nrracing.com/product-p/99101-zh8-ajust.htm

If you are getting fouled plugs, and the engine is dying out at higher rpm try turning the adjustable jet in to restrict the amount of fuel the engine is getting. If your plugs are white or the electrode has black speckles on it turn the adjustable jet out to allow more fuel into the engine.

Lastly, I recommend installing a fuel return line. This line tees out of the fuel supply line from the pump to the carb and allows excess fuel to return to the tank. Some may not need to do this, but its cheap insurance against an engine that isn't running quite right. Here is an example of what I have done. The picture shows my engine bay with clear fuel line. My engine would flood the carb before I performed this last step, and with a good pulse signal and a quality pump it is likely to happen to you.

Re: Zongshen 625cc
 

Thanks for ALL the great recommendations and the responses. I will do all of them and let y’all know! Thanks for the info as well. Have a great Day guys!

Re: Zongshen 625cc
 

If you use an on road or car oil, you should put a zinc additive in the oil. Lawn or off road or racing oil has it but due to emissions on road does not. If you have an oil pump/filter engine you can get away without but still a good idea to use it.

Re: Zongshen 625cc
 

Thanks guys I performed all the work, oil change with Amsoil full synthetic 10-30. Replace plug with a Brisk Premium LR 15 ZC, Cleaned carburetor it was nasty. Fuel shut off and fuel pump you recommended. New fuel lines. Fuel filter, oil filter. It cranked right up. Just had to adjust carburetor. I crapped my pants !! I took for a test drive and hit excelled at or and popped a wheelie WOW.

Re: Zongshen 625cc
 

Good to hear!