View Full Version : Wedge 1980 TR7 Fuel injection questions

04-20-2012, 09:23 PM
Pardon my ignorance but this is my first PI car that I'm working on and the Haines manual is not clear on PI system. I took this off because I saw the holes for the throttle springs were worn out and about to wear through the linkage arms. I have since discovered what looks like a throttle position sensor that is broken. That is the first picture. Am I correct and where can I get a new one? Also there must be a wire that comes off the sensor and would go somewhere. I'm thinking to the next picture where you see the spade terminal with out a wire? The black wire is a ground wire and goes onto what looks like some kind of coil that is mounted above the throttle sensore. Also what is that thing?
On the other side of the car I discovered that the oxygen senor is not plugged in anywhere. Any ideas where it goes?

04-20-2012, 09:29 PM
pic 2

04-20-2012, 09:37 PM
The TR7 just has a switch that contacts at full throttle, not a position sensor like the TR8.

You should probably get a hold of the factory manuals, you can download copies here:


Poke around in the "Triumph_Articles" folder.


04-20-2012, 10:49 PM
I too recommend the factory manual with it's FI specific section and troubleshooting chart. Possible a PO put headers or some such on it that did not have the threaded bung for the O2 sensor. Do not despair, Good Luck

04-21-2012, 08:15 AM
Just a quick search on the net came up with finding the switch at Revington and they also have that solenoid. Sure would like to know what they do? Anyone order from them and how does the shipping work? Heard of some horror stories with shipping from England particularly from UPS. Any suggestions for domestic sources?

04-21-2012, 09:44 AM
Regarding shipping from the UK, I've not ordered from Revington, but have used Rimmer and Robosport. No problems with either, small items go post, and take less than a week. I also ordered some exhaust pipes, which came UPS, no problems there, either.

Here is what the throttle switch does:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
A contact type switch is fitted to TR7 models and is located on the throttle body in the engine compartment. The switch contacts close when the accelerator pedal is fully depressed, signalling to the E.C.U. to lengthen the time that the main injectors are 'open', thus supplying extra fuel for the acceleration required.[/QUOTE]

04-21-2012, 09:50 AM
Could the solenoid be the "overrun valve"?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
Overrun Valve
This second air flow control device bleeds air into the engine inlet manifold, via the plenum chamber, when the manifold depression is high and thus maintains combustion during engine overrun.
The valve operates independently of the electronic control system and on TR7 models is incorporated in the throttle butterfly connecting the constant depression region between the throttle and the Air Flow Meter measuring flap. On V8 models it is a separate valve on the side of the throttle body.[/QUOTE]

04-21-2012, 09:56 AM
Looks like I need to get this all working. I have noticed that there is a lack of power upon acceleration. I've got to figure out now what that solenoid is used for too and all the electrical hookups for this. The guy I bought the car from had no mechanical ability and the garage he took it to for what I can see did lousy work. Plus it's a California car in Ohio and the old Triumph techs here never seen this fuel injection system.
Dale I did download some of the info you provided but it was late last night and now I've got to get to another problem to attend to.

04-21-2012, 10:49 AM
I do believe it is the overrun valve. Should i even be worried about it. Seems it is only for emissions?

04-21-2012, 11:01 AM
I do believe it is the overrun valve. Should i even be worried about it. Seems it is only for emissions?

I believe it is primarily for emissions, it keeps unburnt fuel out of the exhaust. But it is probably better for the engine to burn the fuel, too. If you still have catalytic converters in your system, you will want to avoid dumping unburnt fuel in them, too.

04-21-2012, 01:42 PM
Plus it's a California car in Ohio and the old Triumph techs here never seen this fuel injection system.

The TR7 FI system is straight Bosch L-Jetronic. Maybe try a BMW, VW or Alfa mechanic who works on cars of that era? It also means that you can likely find the parts under the Bosch part number, which is often on the part (perhaps under a Lucas sticker).

You can find some listings here:


There are also some technical nuggets on the Wedge Lab site:


04-21-2012, 06:49 PM
Yes i do have the cat. converter on. In fact it was brand new last year right before I bought the car. I think I read that the solenoid releases the intake manifold pressure after hard acceleration and after releasing the accelerator.
I assume there is a plunger that pushes against some kind of valve that releases the pressure but there are no moving parts in it. Apparently it must have broken before and ether the part was unavailable or the shop didn't think it was necessary to fix. There are some loose wires hanging around the throttle body where this attaches that I've looking for a home for some time now. One wire has a white tube like thing kinda looks like a in line glass fuse holder. Wonder if that's it. Got to get it's power from some where and I thinking that the throttle switch may be to trigger the solenoid.

04-23-2012, 11:44 PM
Does you car have A/C? There is also something to bump up your idle if you do. Could be what the solenoid is.

Have you downloaded the parts catalog from the link I supplied? I think one is there, might help figure out the part numbers. If you can find a factory part number, you can check with TRF, they actually seem to have some of the odds and ends.

04-24-2012, 07:20 PM
Thanks Darrell
I did down load 2 items but been so busy with another household project and trying to keep my business afloat this month I haven't taken the time to read it all. However somewhere i read that the solenoid is to reduce the manifold pressure after heavy acceleration. suppose to help with emissions. Looks like a rod would push out and bump a paddle on the linkage which opens the butterfly a bit. Could easly do what your suggesting too.
To answer your question I do have AC in the car. (non workingI think). So you may be correct. On the other hand a customer of mine today, an old Triumph tech said he thought the throttle switch may be for cutting out the AC during heave acceleration for added power. Don't know who is correct yet. I also have an e-mail out to the old service manager for the Triumph MG Jaguar dealership as to what he thinks. We've become friends over the years and he has a TR8 PI.

04-25-2012, 08:14 PM
Revington just e-mail me and dos not stock ether part and does not anticipate ever getting them. I went to local BMW, VW and Volvo shop today and no one has ever seen one. However one of my Chevy customers saw me walking in with it and we got talking and he thinks he has a nitros switch that looks like what I need. He said it runs off a cam on the side of the throttle body just like mine. If his does not work I'll will need to come up with something. Going to try to a Goggle search for a roller micro switch.
Need to know the wire hookups too.

04-25-2012, 08:49 PM
If you can find this page in the parts catalog, it does show some switches and such, and I checked a few parts and they came up available with TRF.

As for the wire, you may need to find a correct wiring diagram, find the part, and trace wires.

04-27-2012, 11:04 PM
Darrell_Walker you the MAN!! You The MAN!!!

I was going to thank you Wednesday night for all our efforts but got too busy to get on BCF. I checked out TRF's site and the numbers were good so I called Thursday morning and they had one of each. There were on the front porch when I got home from work today. Exact items. I had mentioned that one of my customers had a similar switch he used on his nitros injection system on his drag bike and he gave it to me today and other then the color and no roller on the end they are identical. Even the mounting holes lined up perfectly. Suppose to be a high of 42 and a mix of snow Saturday so I'll install Sunday at 57 degrees.

04-27-2012, 11:31 PM
Glad I could help!