Finally Going Single! Part 2 by cohbra

5-3-2012

After failing to find anything wrong with the ignition, I checked the one thing that I should have checked first, but like an idiot, I didn't; I checked my plugs with a MM and found that 2 of them were bad. I ignored them all this time since I had just put them in.

So... After installing them, the car fired right up without any issues. It seemed to be running good, other than being cold, so I backed it out of the garage to take it for a slow drive around the neighborhood to check it out. Shortly thereafter, I noticed I had low fuel pressure and it died on me. It was acting like I had the exact same problem at first, so I pulled the plugs to check them out and they were completely dry this time. After some serious hassle getting it back to the house, I found that my fuse had blown for my fuel pumps and I remembered that I never bought the 30 Amp fuse that I had intended to run. After putting in the 30 Amp fuse, it fired up fine again, but my fuel pressure was only at 20 psi @ idle. I adjusted the regulator up to 40 psi and then the 30 Amp fuse also blew.

After studying the spec sheets for the pumps, and some talk with a company that specializes in the Walbro high pressure/high flow pumps, I determined that a 30 Amp fuse should be more than enough for the 2 pumps, as well as the wiring I have in place, which left me with what is most likely a bad pump. 

I disconnected one of the pumps to see if I could identify which one was bad, and the first one seemed ok initially. The fuse was holding up, but the pressure was low again. I tried to adjust it back up to 40, but it won't go above 26. 

Of course, I got called back to work again, so I haven't had a chance to check the other pump to see if it responds the same way yet. I've been thinking about my entire fuel setup now and I'm concerned that I may have too much restriction in the -10 fuel line for both of the fuel pumps. Either that, or I have something in my fuel filter that needs to be cleaned out so when I return home, my first order of business will be to clean the filter element. I have also decided that I will run a completely separate power wire and fuse for each fuel pump which will allow me to use the N/C connection on each fuel pump relay to light a red LED if the relay looses power indicating a blown fuse. I might even tie these into the datalogit.

I also have to say that I'm very suspicious of my fuel filter as well simply because I just made all of my fuel lines and I suspect there is still some dust in them from the rubber when I cut the hoses. I tried to flush them out before, but there might still be more in there I suppose. This would also explain the high load on the pumps but the inability to get more than 26 psi at the FPR.

Also, here is the chart for the Walbro 255 Ltr/Hr pumps if anyone would like to check it out for themselves.

http://autoperformanceengineering.com/html/fpspecs.html