canbaufo

Well this is a weird issue that I have caused somehow. I was recently working underneath the car and noticed the positive wire to my inline booster pump wasn't very snug. I tightened it up carefully and slowly, but the "+" post broke off the pump anyway before it would ever get snug. Part of the post remained, but not enough to use the nut to attach the positive wire.

Soooo, I used some JB Weld to attach the wire to the post as a temporary fix. It attached firmly but I really caked it on and that may have interfered with conductivity. The car wouldn't run right after that (it ran perfectly fine before I ever touched the "+" post) and was lean without enough fuel pressure. I assumed that the JB Weld just couldn't conduct electricity, as I could no longer hear the inline pump kicking on when turning the key to run. I tried to repair the post but it wasn't happening, so I ordered a Walbro GSL - 391 (190 LPH) inline pump.

After installing the new Walbro inline pump, it runs exactly the same (lean and low pressure)! I double checked everything during the install and was very confident in wiring, direction of flow, etc. This leads me to believe that maybe what I did with the old inline pump actually killed the intank pump, since it ran exactly the same with two different inline pumps.

So a poor connection of the positive wire to the old inline pump killed the intank pump (or a relay to it)???

Should it even be able to run with a live inline pump and a dead intank pump????

I may bypass the inline and see how it runs on intank only. I would guess there is some type of relay or fuse for the intank pump ...and it must be located under the car. I am hoping it's just a relay for the intank pump that got fried due to my finicky JB Weld connection of the positive wire to the inline pump (old one included with Powerdyne kit many years ago that was installed by a mechanic friend).

I haven't started troubleshooting yet and thought I'd post this first for suggestions on the easiest way to do this by process of elimination. I know a better intank pump is the way to go for a blower car anyway ...but I was hoping to delay that until I actually use a blower with more than 6 - 7 PSI.

Thanks in advance for any suggestions.

Injuneer

Have you verified that the inline pump is running? Did not see that mentioned.

How is the inline pump powered? The typical way is to run a +12V wire directly from the + terminal box near the battery, with an inline fuse, to a relay at the rear of the car. The relay is connected to the + wire for the stock pump, so that when the stock pump runs, the inline pump also runs. The grounds for the inline pump and the signal side of the relay are done with local chassis connections. Is that the way yours is connected?

canbaufo

I haven't had the car off the ground yet since installing the new inline pump, but I had my wife turn the key on while I knelt down listening to and watching it. I saw the fuel line in-between the inline pump and tank flex a bit and I believe it was the inline pump that I "heard". I observed wiring very similar to what you describe if not exactly and confirmed a fuse on the positive wire (visually it did not appear to be blown). The positive wire was plugged into a little box on the chassis that had other wires attached to it and the negative wire was grounded to the chassis.

Long term plan (and sort of short term too) may be to leave the old intank pump for dead in the tank and cap off the line. Then tap into the tank in two places and run two inline pumps that will Y - into the main fuel line. This way the pumps are where you can observe them and work on them without removing the tank; also, if one fails the other one will keep you going without having to work through a dead pump. Two pumps in parallel instead of in series with each other. I figure two 190 LPH inline pumps would be sufficient to feed my future ~10 PSI / 355 c.i. setup. This way I will not have wasted money on the Walbro 190 LPH inline that I just installed.

I've read something about a relay being under the driver side kick panel and that you can listen for it to "click" like a switch when you turn the key from off to run and back again. Figure it would be the easiest place for me to start troubleshooting, as the car could remain on the ground. Also, via search I am reading that the fuel pump fuse is actually labeled "PCM IGN" and is fuse #5 in the instrument panel, ...so I'll be checking that out too.

Thanks for the post, any other thoughts?

Injuneer

If it's wired like I explained, if you hear one pump running, there is power being supplied to both of the pumps, as long as there are no breaks in the wiring to the inline pump, the fuse in the hot wire for the inline pump is not blown and the inline pump relay is healthy. If the #5 fuse was blown, or the stock fuel pump relay under the driver's side kick panel was faulty, neither pump would be running.

Shoebox has the info on the fuel pump wiring:

http://shbox.com/1/1995_pcm3.jpg

.... and the location of the fuel pump relay:

http://shbox.com/1/fuel_pump_relay.jpg

I'm sort of surprised that anyone who has been a member here for 13 years is not familiar with Shoebox's site.

You have to figure out what is running and what is not running.

The "little box on the chassis that had other wires attached to it and the negative wire was grounded to the chassis" is most likely the relay for the inline pump.

I have dual Bosch 205 LPH pumps. The Bosch pump can actually flow that amount at higher pressure than most pumps, and I run my Bosch 78 #/HR injectors at 58psi. One pump is in the stock in-tank location, and runs all the time. It is adequate to supply the fuel required for the engine's 500 flywheel HP output. When the nitrous switch is armed, the second pump turns on. Capacity is more than adequate for the 300-shot of dry nitrous.

The suction line for that pump is connected to the bottom rear of the stock fuel tank. The outputs from the two pumps come together near the fuel filter through an NOS -6AN x -6AN "wye" connector, through a SX billet fuel filter in the stock location, through a -6AN braided S/S line to the back of the engine, where the single line splits through another NOS "wye", sending a -6AN braided line into the rack end of each stock fuel rail. The return line comes of a -6AN fitting welded to the diagonal cross-over tube between the front of the two rails, runs to a Weldon adjustable fuel pressure regulator under the cowl, and then back to the tank. All the plumbing it braided S/S.

canbaufo

I've used Shoebox's fantastic links many times over the years, thanks. These days I'm more focused on my motorcycle and Jeep ...just getting started with this issue on the Camaro. Well ....turns out I had a freak occurrence. I pulled the driver kick panel and checked the relay, clicked with the key being cycled on and off. Checked the PCM IGN fuse in the I/P panel, perfect condition. Looked under the hood for the fuel pump primer connection and couldn't find it. Looked around a little more and found .....a plug wire had fallen off .....

So all is well now and I have a new inline fuel pump I didn't really need but ...heck it's a nice upgrade over the crummy one I had that was manufactured in 1996 lol. What totally threw me was two things; timing of the event and A/F ratio observed.

I had only worked on the rear suspension and fiddled with the old inline fuel pump as previously described. Then immediately upon the next drive it's running rough and my wideband was reading very lean. This lead me to believe the JB Welded positive wire on my inline had caused a short or something akin to that. For me it's certainly counterintuitive to think that my wideband would read lean when a plug wire is disconnected, I would think unburnt fuel would read RICH, not lean ...learn something every day.

Well, actually I'm happy with the outcome and it runs better than ever. Obviously I will need to upgrade the fuel system at some point though. Thanks for the great detail on yours, what do you think of the twin Walbro 190's idea? I really like the idea of running two pumps in parallel and having both of them external.

Injuneer

Whether it's a wide-band or a stock narrow-band sensor, its an oxygen sensor, not a "fuel" sensor. It can only measure the O2 content of the exhaust, not the fuel content. A misfire puts the oxygen and fuel in the exhaust, and the sensor sees only the O2 and reads "lean".

canbaufo

Makes sense, I've learned that before and forgot. So what do you think about the twin inlines in parallel idea?