85 series III won’t start

Do you have power at the pump or not?

Hoses as they should be. There’s a big argument for original parts as long as they work. This excludes all hoses from the pump forward, while you’re at it, but do make sure the next pump isn’t broken and not trying to turn backwards. Unless you don’t have power, then it’s probably time to make a test light and go through it all.

The pump works, well it hums and vibrates. Nothing comes out. It works while cranking and works with hot wire. I tried switching tanks. Still nothing.
The old pump ran also and must have been running correctly as car ran for long time.
I’ll have to get wife out there again to switch tanks while I listen for some clicking.
And just work my way upstream.
If I remember correctly just removing hose from tanks to changeover gives you fuel leaking out of the hose ( at changeover). Hose lower than tank I guess. So that would confirm fuel to there. It seems like changeover mechanism would default to one side being open??? Any ideas there?
So pump probably running backwards but why did it die in first place with old pump? Could be two separate problems happening at same time. I hate when that happens, this stuff is tricky enough as is.
Any this should be simple enough to check.
Check for fuel coming out at changeover from both tanks. See if pump can suck fuel from a can. Go from there and at least get fuel to fuel rail. Then see if I have a whole other problem.
Thanks again for your help.

Two reasons the pump doesn’t produce any flow are that the pickup inside the tank is blocked and the pump sees no fuel (but unlikely on both tanks, or that the pump is defective. So you should first try a new pump, or the old one if that was still okay.

You should buy a few feet of injection hose, 8mm, and route the fuel back to the tank. When you’ve got the problem figured out you can use the hose to get rid of the old fuel hoses you still have in the trunk. One of the very few parts where it is not up to debate if the old parts work better or not. One crack and there’s gas everywhere.

Hose will spill fuel until the tank is empty (both tanks if you’re lucky) and valves default to LEFT tank with no electricity.

This appears to be the same problem I had recently with both fuel tank filters blocked.Time to flush both tanks and change fuel filter.
I noticed that a lot of these cars are having the same issues,it must be age related.Maybe the tanks should be cleaned every 10 years to prevent this happening.
By the way my car is still running great.

1 Like

SIMPLE:

Remove fuel pump from trunk. Put on bench. Put a hose on the pump. Put hose in some gas. Connect power to the “+” and ground to the “-”. on the pump. You should have fuel coming out of the other end of the pump!

Simple!

RG

For the record, David; fuel goes through(!) the non-return valve to the filter - the extra hose on the valve, vent-line, is connected to fuel return line. With pressure from the pump, the non-return valve opens to the filter/fuel rail, and closes the vent-line. When the pump stops, fuel line pressure closes the rail line, retaining rail pressure - and opens the vent-line…

Frank
xj6 85 Sov Europe (UK/NZ)

**
The intakes are at the low point in the tanks, Tom - but the flow depends on the fuel level in the tanks…

With full tanks; there is not a trickle, but a flood of fuel - and even with the tanks low; considerable fuel is (should be) flowing when hoses are disconnected - so some care must therefor be taken to reduce spill into the well.

Disconnecting a tank hose at the changeover valve; fuel will flow from that tank, and depending on the tank selection; also from the filter back through the pump and out from changeover valve - unless the non-return valve functions as it should. And if the changeover valve is defective; fuel will also flow from the other tank…

If changeover valve-to-pump is disconnected; fuel will flow from the selected tank and from the filter - non-return valve and selection position depending…

So disconnecting hoses can be used to assess blockages in lines and components, but it requires good knowledge of the lay-out and functions. And the flow rate will in any case be influence by tank levels - and leaking fuel is a hazard!

A shortcut to eliminate tank filters/hoses as a factor is indeed to connect a can of petrol directly to the pump - clamping the changeover-to-pump hose, and testing the pump at the same time. The non-return valve can be tested by connecting the pump directly to the filter, of course…

The pump itself can also be tested in other suggested ways, but(!) a properly new pump will deliver 100+ psi - so be careful!

Frank
xj6 85 Sov Europe (UK/NZ)

That’s what it does and the pumps, at least the new ones, have a non-return of their own…

Gotta work fast or you’ll have a real mess on your hands !

Tidbit:

Small pieces of wood dowel make excellent fuel hose plugs. Grind one end to a point for easy and fast insertion into the fuel hoses.

Cheers
DD

Thanks for all responses. I have some news of a definite problem and easy fix. I wired the pump backwards. Do tons or tomorrow I’m going to put new terminals on and reconnect. Right now I have wires under screws. Not cool, pump works fine. Hoses all seem to be clear.
Tried starting car, almost started but no dice.
So first I need to get everything in boot reconnected, clamped down and tightened up.
Then back to original problem of no start.
I’ll go back thru the older original suggestions and see what I can do.
Thanks again

**
If so; it will indeed run backwards, Tom…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

Neat as to electric motors…

Carl

Ok I’m going to go back at it.
And a special thanks to Carl and Frank for their helpful comments. Those solved everything! Always a smart Alec or two in the crowd. Hey, it was a 50/50 shot. For some reason I seem to be wrong more than 50% of the time, and that’s AFTER I think it over.

So Im sure, “famous last words”, the injectors are not firing. Until I get them working it makes no sense to worry about anything else.
When I do the bullet wire thing I hear a faint noise. It’s not an injector. It’s not the cold start though it seems to be coming from there or below there. It’s kinda of a “zzzzztt”.
I remembered I had a set of noid lights and so I checked injectors and cold start and got nothing. I ran thru a series of tests that I found here or elsewhere. I have to find them again and try again.
Anyway I get that weird zzzztt so that wire is continuous and hooked up to somewhere as I didn’t change anything.
I did fool with main relay and pump relay and diode pack. Could have broke a wire there or hooked it up wrong.
(Why did they put that smack dab in middle of car so you have to lean over the maximum distance and then tuck them up under that brace so you can’t see what you are doing).
But I digress.
Though car was running fine when it died so something must have failed before I started fooling with it.
Any help would be appreciated especially from Carl and Frank as they seem to be the leading experts on these matters. I kid.

The bullet connector comes from the coil - and goes to the ECU… the ECU grounds all 6 injectors at once, sharp click, on every third break (every engine revolution and the wire is very sensitive). The other side of the connector goes to the resistor pack under the air filter, constant power, but with some resistors in line.

If it does a buzzing sound when the wire is tapped together, and that noise directly reacts to the bullet connector, I have no idea what it is. Or could be. Power on both sides of the injectors?

If it is constantly buzzing it’s the now working fuel pump and the fuel passing through the regulator. The cold start injector, unplug it if you suspect it but it’s a separate circuit and only comes on below 35? degrees and then only for a few seconds - heated bimetallic sensor.

It could be the coil or the ignition amplifier boiling away! But how, I don’t know. I t h i n k you can try grounding the bullet connector, ECU side. Different?

Thanks for reply. I’m at work now will look into it a bit later. Problem is car died in driveway where it gets afternoon sun and I bake out there. I’m in Chicago and it’s been 90 with near 90% humidity.
So at least we can rule out cold start device causing a problem. And with this global warming maybe I can take it off and throw it out.
The bullet wire does that noise every time you touch it. Don’t recall if it continues if you hold wire on there. I don’t think so, I’ll check when I get home.
The injectors had 12v on both sides which I think I read is correct.
Noid lights didn’t flash but I remember in a checklist it said connect noid differently and check for flash. Then I think it did. Gotta find that checklist as I’m thinking that might be useful info.
Car still fires up perfectly, immediately, every time with ether.

12v both sides is good. Now, the bullet should not fire every time and it should not buzz. Try again and try to locate the buzz. You miswired the fuel pump, so you’re have to be just like me, and so I’m confident you’ll get this going again.
And of course the golden rule of troubleshooting: anything you looked at is suspect.

Is getting to rain any second so I couldn’t do much. I tried to record video of buzz sound. Sounds like it’s coming from around cold start housing. The buzz comes momentarily as I touch wires together.
Took picture of inside right fender. That silver box is diode pack you mentioned? Took some other pictures to see if you can see anything obvious.





Video didn’t work. Cicadas are so loud you can’t hear anything else. I’ll try it in morning

Solver box is resistor pack. Not much to it, smd resistors on a pcb… you have power.
Diode pack is the red relay thing on the bulkhead.

It has to be something you did. It can’t be the cold start circuit but you could disconnect that. I hope the rain helps with the weather. Nothing obvious, sorry.

**
Yes, Tom - but the 12V does not mean there is power…:slight_smile:

Use a 15 Watt test lamp; connected between ground and the ‘resistor pack’ wire on the injector plug - it should be fully lit. The 12V on the ‘ECU wire’ at the connector is ‘parasitic’ and has no power to light the test lamp. Also, that the noid test lamp fails to flash/flicker during cranking may imply ‘no power’ to the injectors - or indeed the ECU…

The ‘buzzing’ indicates that current is flowing - sounds like arcing in a bad connection. It would be helpful to find where the buzzing comes from - it could be a relay failing to operate properly. A quicktest would be to swap the main and fuel relay - though I do not really suspect the main relay; it’s easily checked.

Another possibility is a short to ground, arcing - somewhere. Try an ammeter (set first to 10 A) between the two (disconnected) bullets - it would show current drawn between ECU and coil negative. I haven’t the foggiest what it should read - but it should not be very high? If the ammeter fuse blows, or high current shown - there is likely a short between the bullet and ECU…

Even negatve test results are of value…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

Thanks for ideas guys. The noise does sound like an arcing. That’s a good way to describe it. It seems to be coming from cold start housing or below, but I don’t think there is anything below it. I think I’ll try and disconnect it to see how that affects noise.
The main relay is new. And I checked it and fuel relay by removing, hot wiring to 12v and contacts open and close properly. The diode pack(red relay looking thing) also checks out. But I’ve done that a couple of times so could have done something wrong reconnecting. But remember, originally, car started and ran normally for 1-2 minutes, chugged and died. So something failed before I started messing with it. Since then other things are possible.
I’m going home early to fool with it.

In a related issue. I’m worried that ecu might be shot. I have one from a VW Vanagon of same era. 82-85. 4 cylinder of course.
Might that be a replacement or am I dreaming. Getting ahead of myself here but was wondering.
Thanks again