TheSamba.com :: View topic - First Post...Need Help, go figure?! Fuel Pump Issue

Thu Oct 02, 2008 7:46 am

I've lurked around these pages for about a year now and picked up lots of help and info just by absorbing all the postings. Overall, this has been an extremely helpful resource...thanks all all the very knowledgeable folks who contribute.

Here's my latest problem:

91 Vanagon GL
Stock 2.1 w/ 204xxx miles
I've had this for almost a year and it's my daily driver.

After running errands and driving the kids around town yesterday for about 1.5 hrs, while at a stop light, the van idled very rough for about 5 seconds and then quit. Van would turn over, just wouldn't hit a lick. Icing on my crap cake was that it was rush hour and I was in a left turn lane at a major intersection....with my two dogs and 4 year old son in the back. It took quite a bit of effort to stem my colorful vocabulary arsenal that I picked up over 11 yrs in the Navy. Ended up starting to push the van across the intersection with the help of a couple of guys. The van seems to bring out the "do good" in folks. Halfway through the intersections, we had a cop "ram" the van into a parking lot and called a wrecker. All the while my son helpfully informing me that we'd been hit in the "butt" by the po po. While waiting for the wrecker, I was fiddling around and noticed the fuel pump didn't turn on when the ignition was on, as it should. Figured it was a no brainer and it's either the fuel pump or the fuel pump control relay.

Welllll, today I went out and just for giggles, turned the ignition on and to my surprise, I heard the fuel pump purrr. Hmmmm...engaged the starter and VIOLA! It started right up and ran perfectly. Well....at least as perfectly as it did before. Perfection is relative.

So what gives?? I was thinking maybe "vanagon syndrome"? My only hangup with that is that I've been driving it hard for almost a year with no problems, and the van's got over 200K on it. Wouldn't "vanagon syndrome" have surfaced before now? Or is there no rhyme or reason to it ?

Eagerly await replies....thanks in advance!

Jason

Thu Oct 02, 2008 8:26 am

Might be a grounding issue. Clean all your ground connections and see if that helps.

Thu Oct 02, 2008 8:27 am

fuel pump relay is probably on its way out. replace it..can't hurt anything.

Thu Oct 02, 2008 8:28 am

how is your ignition switch...did you check it with a meter?

Thu Oct 02, 2008 8:28 am

Normaly I would not subscribe to throwing parts at a problem. You have a vehicle with parts and wiring that could in some states be considered antique. Get a 12 volt test light and while your engine is running perfectly, probe the relay, ignition switch, coil, etc and get an idea of where power is when the van is running correctly. Also, take the time to clean all your grounds. Not spray them off, but remove and scotch bright the connectors and where they attach. Also you can make up some jumper wires and carry them in the glove box. If the relay is intermittent you should be able to unplug it and jump across to run the pump. You could also unplug the ignition switch and jump across it. I realize the symptom was the pump not running, but did you check for spark? If both are missing, you might be looking at the ignition switch. Don't be afraid to buy new parts as long as they are quality. Lastly, get a bentley manual and learn how to read the wiring diagrams. Once you get the hang of the diagrams they are quite easy to understand.

Thu Oct 02, 2008 9:17 am

Thanks for all the quick replies.

Grounds: My grounds "should" all be good. I've previously cleaned all the grounds. Barring any faulty ground wires, everything should be grounding properly.

Ignition: I didn't check for a spark, as I didn't have any tools with me. I just removed my tool bad that morning to tinker with something in the house.

Bentley: I got the manual and am fairly adept at reading a schematic. That's what led me to believe it's either the starter relay, or the starter itself.

I'm going to recheck/clean the ground wire coming off the pump today. I'm a commercial pilot and leave for a three day trip this afternoon, so my efforts will be limited today. In the meantime, I'll see if I can't get ahold of a starter relay. I agree in not throwing parts at a problem, but a relay shouldn't cost too much and it makes sense that a relay would fail intermentently before it goes completely caput. Right now, I'm favoring the starter relay. Bentely does a great job showing the wiring to/from the relay, but where the heck is the little bugger. I'm thinking under the dash somewhere....but I'm not real positive. I'm gonne go out now and have a look. Thanks all.

Jason

Thu Oct 02, 2008 9:31 am

I think you mean the fuel pump relay. Your initial diagnosis was on the right track.

The FP relay is in the relay box hanging on the left wall of the engine bay, above the coil. Two relays: left one is main FI power supply, right one is for the pump. The main FI relay closes with key on, powering the ECU, which then triggers the FP relay to power the pump. Swapping the two relays does no good, because both have to close for the system to run. Luckily they are the most common Bosch SPST relays, and can be found at any auto parts store. You can jumper this type by connecting 30 to 87; these two pins are always the ones that make a "T" to each other, flanked by the pulldown coil circuit pins. There are also the same type of relays in some positins on the main fuse panel that can be stolen for testing. Nothing up there has anything to do with engine operation except the ignition switch itself and the wiring to and from it via the fuse board.

You can't rule out ignition switch, though. They often fail intermittently like this on their way to complete failure.

Thu Oct 02, 2008 9:55 am

tencentlife,

Yep, I did mean fuel pump relay....not starter relay. My fingers are often quicker than my brain with this keyboard.

Anyhow, I found the relays. Presently, both are working properly. EVERY time I hit the ignition, I can hear the pump wrrrr. That being said, I'm gonna replace both with new parts. The bad part about these intermittent failures is that they're difficult to finitely troubleshoot. I guess I'll throw in these two relays, reclean the ground from the pump and hope for the best. If I break down again on the roadside....the problem still exists. Wish there were a better way. AAA, here I come.

When you say "ignition switch", are you refering to the whole ignition assembly itself? The tumbler type assembly the key goes into?? Forgive my terminology (or lack of)...as I've never really delved into that part of a vehicle before.

Thanks again all.

By the way, tencent, you're on my radar for a possible engine upgrade in the future. I'm also dealing with some border line oil pressure issues as well. 20-50 oil, proper filter, and sub 90 deg days keeps the buzzer off....but I feel like it's kind of a band aid at this point. I'm certain an external oil cooler would help as well, but that's probably just delaying the inevitable. Other than that, the engine pulls real strong (again...relative)...idles a little rough, but I live with that for now. I know there's lots of posts on this already and I'm all schooled up on it....just need to find the time to hook up a pressure guage and see what the actual pressure is and go from there. Thanks all!

Jason

Thu Oct 02, 2008 10:44 am

By ignition switch, what is being referenced is the electronic component found UNDERNEATH the ignition key tumbler assembly. Here's a pic stolen from GoWesty's website. About 12 bucks. Does require removing the steering wheel to replace, but pretty easy job.

Thu Oct 02, 2008 10:45 am

Oops. I just looked back and saw your van is a 91. That means your main FI relay is a special type, but the FP relay is still the common Bosch SPST. Look at Bentley p.97.206 and you'll see that the Digifant Control Unit Relay has an extra connnection and internal diode. So a common relay won't work there, but it will on the FP side.

The ignition switch is the electrical component housed within the steering wheel locking asembly, of which the key cylinder is also a part. To change the switch involves taking off the steering wheel and sliding the lock assembly off the steering shaft tube, which is all pretty easy, so you can remove the little setscrew that retains the switch component inside the lock assembly. But you can get at the wiring connections to hotwire the car just by removing the plastic trim around the steering column and pulling off the multi-pin plug from the bottom of the switch. Make sure if you hotwire that the key is in the ignition lock and turned to "on" anyway, or the steering wheel will lock up on you!

Yeah, it sucks these things are so intermittent when they begin to go. Give me an outright failure anytime; the problem is there and I can go find it. It's so hard to catch an intermittent failure in the act, and they hardly ever occur when you're in a good place. They never screw up when they come in for their shop appointment, that's for sure. I can't count the number of times I have had a customer finally leave their car with me so I could drive it myself every day until it would screw up, and I would keep whatever diagnostic gear I needed with me in the car so I could perform tests right then and there.