Hello Everyone I am hoping to get some advice on a problem I have recently encountered with my 91 Suzuki Carry after recently changing out the fuel pump. After having this little truck for the past 7 months with no issues and lots of fun, I finally encountered its first problem. My son had been driving it and it died. He said there was a light on which he said had something to do with the manifold temp being too high. I looked up what this light might mean and it seemed that the Cat could break up and clog the exhaust. I assumed this was why it wasn't running ( I should not have made this assumption and should have dug a little deeper).I removed the exhaust at the Catalytic converter and sure enough there were some big pieces that had broken off and were obstructing the exhaust. I cored it and cleaned it out entirely. Assuming the problem was fixed I tried starting it but immediately noticed that I didn't hear the familiar ticking noise that occurs from the fuel pump when turning on the ignition. and predictably it wouldn't start. I pulled the pump and checked to see that the connector was getting 12V which it was. Tried connecting 12V directly to the pump and nothing. I then ordered a replacement pump which I found one for $80 CAN on Ebay and waited for it to arrive. Three weeks later ti arrived and after splicing the old connector to the new pump and connecting everything back up it fired right up. I noticed immediately some difference with the new pump in terms or its behaviour when turning on the ignition. The old pump would run for 2-4 seconds and then shut off. The new pump continuously runs with the ignition on. Initially, while I thought this unusual I put it to the back of my mind as the truck started and seemed to be running well. Later the next day I took a friend down some trails running the truck for about 30-40 min without issue. The following day my son took it out and got it stuck in a large mud bog. I pulled him out shortly after and he drove it back to the house without an issue. The next day I cleaned the mud off and the following day I fired it up to move some things around the yard. I started it and got out to open a gate.Within about 2 min it sputtered and died. I tried restarting it and after trying several things it would restart with much effort, only after pumping the accelerator and holding it to the floor and cranking for 1-2 min. It would run and rev but after letting of the throttle it would again die after a few minutes and prove to be very hard to start. Before I start trying to trace down a problem with the carb, I have a question about the fuel pump. Should it run continuously or shut off when it reaches a certain PSI? I did connect it to a fuel gauge and it shows approx 3 psi which I think is normal. If I cap the end of the fuel line the pump continues to run and does not shut off. I verified that there is lots of fuel getting to the carb so no obstructions. Rather than not getting enough gas it smells like and behaves as if it is getting too much fuel. I will pull the plugs and inspect tomorrow and look at the vacuum lines. The thing I don't understand is why the old pump would shut off after a few seconds with the ignition on ( is the pump designed to sense a certain PSI and shut off?) while the new one runs continuously. What is normal behaviour for these fuel pumps? I understand that it would run continuously while the engine is running but I don't think it should if the the ignition is turned on. Again, should it not sense when the desired psi is reached and shut off when the ignition is in the on position. Is it possible that if it is designed to do this that the pump is defective? One last thing. When I had the air filter out to inspect it and turned the ignition on gas started coming through the air box. It would seem that the float may have been sticking. Today I tapped the bowl and tried the same thing with the ignition on and it didn't do it. Sorry for the long winded post.lol! A lot if unnecessary info no doubt but I am hoping someone can give me some insight into what the problem might be (i.e. fuel pump, carburetor etc.) Thanks in advance everyone and I look forward to many more adventures in the mini truck! Cheers. Pierce
Just my thoughts. It would seem to me that you do not have the right pump. You state you had to change the connector. In my experience, these type carbs seem to be most happy with 2 to 2.5 lbs pressure. At 3 lbs, you may be overpowering the carb inlet spring (indicated by the excess fuel). Another indication of a wrong pump might be the continuous running, rather than stopping when fuel pressure is built up against the carb spring. Fred
Hi Fred, Thanks for responding. So I guess I was correct in thinking the pump shuts off when a certain PSI is reached. When I plug the end of the fuel line and turn in the ignition it continues to run which I would assume that there is an issue with the new fuel pump. What I find strange is I see different people posting different things about this gen of pump with some saying it is normal to run continuously with the ignition on and others saying it should not. Idea the pump sense when a certain PSi is reached and open the circuit and shut the pump off? No one seems to have mentioned this specifically as if yet.
I am not familiar with your particular vehicle so can only give general thoughts on it based on previous experience. Hopefully someone with more specific experience will chime in. You might do some checking in past posts about this as it seems that there are a lot of problems with the fuel systems prior to them going with EFI (which I have on my 2002 model). Sorry I can't be of more help without physical access to the vehicle. Fred
I had similar no start issue with my 1994 DD51T back in the Mar/ April time frame. After working all winter with absolutely no issues , one day it just decided no to start. I discovered I have the 3 wire fuel pump. I cleaned and checked all the electrical connectors and got good readings. I took apart the pump assembly and made sure the diaphragm was intact. I dropped the gas tank and cleaned it out. I installed a new filter and hoses on the supply side of the tank. I also changed the hose and filter on the fuel return line. I spliced a new clear fuel filter in between the gas supply line and the carb. Now when I turn on the ignition I could see the pump pulsing fuel up to the carb. Like yours, the pump would run a few seconds and then shut off. In doing some research both on this forum and other google searches, other people pointed out that the fuel pump may be cycling off as it is looking for an electrical signal from the oil pressure warning switch that the engine is NOT rotating / running. This is a safety feature built into the circuit to prevent the pump from cycling on continuously when the engine itself isn't calling for any fuel. Sounds logical. I plugged everything back together and it started and is still running with no additional issues, so I never actually found the problem. Upon the advice of other folks on this forum, I did purchase a new 2 wire fuel pump, along with an adjustable regulator. If I encounter another issue I am just going to junk the 3 wire pump and install the 2 wire pump, along with the regulator. I also found out that there is a tilt switch built somewhere in the circuit. Again, I would assume that this would shut off the fuel pump in the event that the truck is in an accident or from being turned over. I never yet found mine but now that I have just received my Danko electrical schematic service book, I may to try to locate it and check it out.
