79 VW Type 2 - Engine Turns But Does Not Start

[sherman931]

Hello, I have recently inherited a family heirloom '79 VW Type 2 - 2.0 L Fuel Injected Bus (Bay Window). I am facing an out of province inspection of the vehicle which shouldn't be too bad once I get a few problems worked out.

Anyway, my biggest problem right now is:

The engine starts intermittently. When it does not start, it at least turns over. It was driven from Alberta to British Columbia about 5 days ago. Previous owners did not report any problems with it in terms of having problems starting it(they are immediate family, so I trust them).

-Temperatures range from -5C to +5C (23F - 41F) (December 2014)
-battery voltage 12.4VDC
-battery age ~ 4 yrs old
-battery posts freshly cleaned, copper wire stripped of corrosion

We have verified spark and the fuel pump presumably works as the bus does sometime start with no issues and it drives around fine. That is the furthest I have gotten so far with my investigation of this issue

To me, the Fuel Injection system is suspect on this one, but that is only a reasonable guess. I would like anyone's ideas on this. If you have any questions or need more information, just ask and I'll do my best to get it for you.

[Wasted youth]

It sounds like by your description that the starter motor always turns over, but sometimes the engine fails to start and run. When it does run, it stays running and operates normally.

I would look carefully at the grounding point on the Fuel Injection wiring harness as a first, easy check. This is a small copper/brass connector using common spade terminals. It is located near center of the top of the engine case, on the Driver's side. It is under the black air plenum, where the large four intake tubes meet.

It will be somewhat difficult to get at with your fingers, and equally hard to see. You should have at least two of the wires from your wiring harness connected here, the wiring harness plugs are female, and the spade terminal on the engine case should be wire brushed clean. The plugs must have a tight, clean fit!

Also, here is another thread that might help:

http://www.thesamba.com/vw/forum/viewtopic.php?p=7468445&highlight=#7468445

[Wildthings]

You need spark at the plugs, not just at the coil. A bad rotor or cap may keep an engine from starting as will bad wires or plugs.

You could also dump a couple of teaspoons of gas into the S boot to see if that will make it fire. These engines have a cold start system which must work if you want easy cold starts.

[sherman931]

Thanks for the quick reply guys. As far as the spark goes, we checked one cylinder for spark and the spark is present. I don't know enough to determine whether it is good spark, but it definitely was there. Oh yeah, and it is the stock distributor vice the Pertronix.

Anyway, I will run with those ideas and see where that gets me. I might not get a chance to get at it for a few days, but will keep you posted. In the meantime, if anyone else has any input I'd be glad to hear it.

[aerosurfer]

Start with an over all tune-up,

Points check,

The FI components all have good clean connections with each other. The Temp Sensor 2 which is screwed in the head by cylinder #3 is both tight and has a good connection.

The Ground strap underneath from the Transmission to the frame is also clean of corrosion.

Fuel Pressure check as well, and new fuel filter (and soon but eventually fuel lines)

Make sure all the Vacuum hoses are tight and secure and not split anywhere

You clearly know it runs, now its the start of chasing your tail. The FI is finnicky when things are not perfect, but very nice to you when everything is in sync. Dont get frustrated
_________________
Rebuild your own FI Harness..My Harness

77 Westy 2.0L Rockin and Rolling Resto!

72 Sportsmobile (sold)
79 Tran$porter... Parts car money machine (gone)

[Tcash]

When it does not start
Is this when the engine is cold or hot?

[sherman931]

It seems to happen after sitting a while => cold start.

[Wildthings]

[Tcash]

Look at the (starting) diagram.
Check and clean these connections.
While cranking the fuel pump relay is switched on by number 50 off the starter.
Also check the connections on the thermo time switch and the cold start valve.

Thanks to Amskeptic
Double Relay Article

Good Luck
Tcash

[sherman931]

Just a little update about where I am at... I removed and cleaned the ground wires as Wasted Youth suggested, unfortunately there was no change. I also confirmed the delivery of ~12V to the fuel pump via dual relay as per instruction in Section 10 - Paragraph 4 of the Bently Service manual.

Wildthings, I have not tried the fuel in the "S boot" as I am unfamiliar with that part. If you could let me know where that is with a description, I will most certainly try it. If you are talking about the +12VDC line coming from starter solenoid terminal 50 to the double-relay terminal 86a, I have confirmed that the voltage is present which energizes the relay and goes on to supply the fuel pump from the battery via terminal 88d.

Aerosurfer, I will also check into the things that you suggested. I not familiar with doing a fuel pressure check, but if you have the time to explain it and tell me what kind of equipment I need to measure it, I will be able to figure it out. Also, not 100% sure about where the vacuum lines are located as I am fairly new to the fixing car game. I think I have an idea, because I see some small, presumably, non-fluid carrying lines with some diaphragm-looking parts and t-junctions in the system. Assuming that is the vacuum system, I will take a closer look.

Tcash, I have cleaned all of the relay contacts, but I will clean the other end of the wires coming from the relay when I get some time. That is not a bad idea at all. That is a beautifully illustrated wiring diagram. Whoever did that up is my hero. Seriously, I can fumble my way through normal wiring schematics, but that gives a much better understanding of how the system is actually linked together. Thanks for that.

Thanks for the input everyone, I appreciate your time responding to my dilemma. I'll update as I go.

[Tcash]

Fuel Injection Diagram Collection

[Randy in Maine]

It would be nice to have the injectors cleaned and calibrated with both the hoses and the inector seals replaced.

Have you done a residual fuel pressure test? I would just leave the pressure gauge on the fuel rail while you sort this thing out.

http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=213

[Waves2day]

Have you pulled out the fuel filter yet to see if it is blocked? Easy and cheap...

Also have you verified the fuel pump is working? Just because you have power to it does not mean it is spinning... Get a jumper wire from the positive side of the starter to the positive side of the fuel pump. If you here it whirling it's good, if you here nothing it's bad.
_________________
Sam
1976 Westfalia Camper Pop-top
1972 Westfalia Hardtop (sold)

[Wildthings]

The S boot is the big black rubber boot between the AFM and the throttle body. You can loosen the clamp on the AFM end and dump a couple of teaspoons of gas into the boot. Reattach the boot before trying to start the engine.

Read up on the cold start system, it has a couple of common failure modes and will effect starting any time the engine block temps are below about 100°F.

[pittwagen]

So where are you located and how did the bus get here from east of the Rockies?

[SGKent]

busdaddy is in BC too.

It could be anything from a bad set of points or lose coil wire to a bad ignition switch.

Let's first determine is the bus is a 49 state or a California manual trans bus because 1979 comes in two different manual trans emissions packages plus automatic.

Your goal is to find which of 3 things is missing

Fuel and Air (wildthings gave you an easy test)
Spark - pull the center coil wire and hold it close to ground when you crank
Compression - probably not at issue.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[pittwagen]

Woops. Missed the line about Alberta and 5 days ago.

Had the van sat for a period of time before being driven to BC? Do you know when the last time the fuel filter was changed?

[aussie angus]

If it runs fine when it does start and you only have inssues starting when it is cold than maybe have a look if the cold start injector is firing. Little thing on the rear of the plenum (looking at you when you open the hatch) that has the same kind of plug as the other injectors. Check it gets power when it should and maybe take it out and check it does spray some fuel. Even if everything else is miles out it should give one little splutter when you first try to get it going if the cold start fires.
Other than that defiantly check that temp sensor on number 3 cylinder is working and then start looking for a bad earth or loose electrical connection, there are many and only one needs to be bad for you to get issues

[sherman931]

Quick a little update... nothing has changed from my last post... but temperature is just above freezing as it has been for the last week and it randomly turned over and started on my last attempt. I ran it for about 15 minutes and turned off the ignition. I tried immediately after and it worked. I then waited about 2 hours and started it up again. It worked.

I suspect it is not the last I have seen of this problem, but it makes me feel good in the meantime. It is a weird intermittent problem. When I get a chance, I will try your guys' suggestions and hopefully I will be able to track the source of the problem and fix it. Anyway, thanks again.

SGKent, I am 97.3% certain that it is a 49 states edition as it was purchased in British Columbia and it is a manual transmission.

Pittwagen, might see you on the road someday as we will be practically neighbours come January (we will be living in the valley). To answer your questions though... it had been sitting for a while in Alberta after the summer months and no, I haven't looked at the fuel filter yet. You are right; that is simple enough to check. I will look into that tomorrow.