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Wedge tr7 fuel delivery

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wrenchinhand

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Ok. My E-Bay TR7 Spider arrived yesterday. I probably should have let Mark have the bid.
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Anyway after sitting for 3 years it needs lots of help. At least it's not a rustbucket. We actually got the car started after dumping the fuel tank and new fuel with stabilizer. The fuel pump is toast. Someone tried before me to get it running. The problem is no power to the fuel pump. Could it be a relay and how do you test the relay? Also where's the best place to buy a fuel pump or does someone have a used one they are willing to part with?
 
Exhange for a rebuilt. 99$ VB But first check the electrics. There is a relay and there is a fuse.

I'm betting fuse if someone was trying to get it going and the pump was plugged. Wiring diagram + multimeter and it should not be too hard. Start by checking the pump hot lead to ground with the ignition on.

[ 04-04-2004: Message edited by: MichaelF ]</p>
 
Right, Fuses and relay, BUT also the ECU will not activate the fuel relay pump if it is not powered either. There are a few other things that keep the ECU from activating the relay so you need a troubleshooting table out of the ROM. That TR7 sitting in the Nevada desert and getting wet/dry over the years is going to have some electrical contacts issues to clean up.

After you verify you have power to the pump and then no pumping action, you might want to try NAPA and have the counter person get the cross reference out for the fuel pump. I am always surprised what they come up with at better quality and less cost than buying the supposed "Genuine" part.
Seems to me that TR7 Spider is EFI so that is an inline fuel pump that is going to have an OE manufacturer anyway that mass produced them for other cars.
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Before you get REALLY carried away, I'd check the inside of the fuel tank and make sure that it's not rusted. I bought a car is similar shape last spring, and the tank was so rusted on the inside that it was getting picked up in the fuel line, and clogged the little screen in the OEM fuel pump, causing it to burn up. I ran thru 2 brand new fuel pumps before we figured out the problem.

As far as checking the pump, pull the plug off of it and using a tester light, see if there's current to it when some is cranking the motor. The incoming hot wire should be white with a green stripe, unless the PO messed with it. If not, the "combined relay" is located behind the glovebox, and you can check for it's operation (it should "click" when the key is turned to the on position), and the wire from there to the fuel pump should be a light green with white stripe. One other thing...there may or may not be an inertial switch on the left front inside fender. If it's tripped or defective, the pump won't get fuel. If it's there, try bypassing it just to test it out.

Let me know if you need pictures...I can easily shoot some with the digital camera and send them to you.
 
>>TR7 Spider is EFI

Right. It's a Bosch unit and many 80's cars like the Rabbit use the same parts. Injectors for example. Since it is a high pressure pump the $99 exchange I see out there isn't bad. It's 239+ for a new one I believe. I'd say a "TR7" one for $99 is a better better bet than a NAPA/Schucks cross reference for $79 ....

True they might be the same part but ...

To troubleshoor you MUST get a wiring diagram. One is in Hayne supplement section.

You can buy a very nice large version at

https://www.wedgeparts.com/#wiring

An overview of the PI system is at

https://www.tr6.org/tr8/L-Jetron.htm

But in general, I'd use common sense and a mulitmeter to trace voltage at the places where it is supposed to appear.

Take some care around the ECU. You don't want to fry it. But I'll bet given the care sitting around, it's a bad connection. A steel brush and a little dielectric grease is handy.

PS the 'inertia switch' you'll be checking is driver side just out from the brake MC. You'll be looking for it otherwise. Black cube with push button. Don't push it BTW. . If broken, don't bypass it unless you wish to perish by flame when/if the car ever rolls
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[ 04-04-2004: Message edited by: MichaelF ]</p>
 
As an example, when I was looking for an inline high pressure fuel pump for my Stag conversion, I went and crossed a 100 PSI pump for a Ford big block truck. The OE "Ford" pump was $285. The counter guy looked at the pump, went back and got the OE "NAPA" pump, we took them both out of the box, both were the exact same part number and manufacturer stamped on the case, same bag of pieces. NAPA pump was $68. So what was the difference? The cardboard box and instruction page, both the OE and the NAPA boxed one had a 1 year warranty.

Second example was the idle speed servo motor for the EFI air plenum. Rover wanted $395 for the servo motor, GM wanted $250, and the Echen part was $35. Take them all out of the box and compare them side by side, they are exactly the same, but the Rover part says (Genuine Land Rover Part) on the plastic bag. The Land Rover parts guy told me just to go buy the Echen part because they made it for Rover and GM.

Point is, a lot of major manufacturers do not make their own parts, they contract them out to their specification, and the spares market sells them without the logos for pennies of the OE prices.

When I worked at Philco Ford as a kid, we took the electronic ignition module circuit board at the end of the line, stuffed it in several different metal cases before potting and packed them into "Ford", "MotorCraft", AMC/Jeep, and OE supplier boxes. The ones with "Ford" cast into the case or packed into "MotorCraft" boxes were $400 from the dealer, the OE ones were $100.

It pays to talk to the counter guys and drink beer with them once in a while at car shows.

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Thanks! As always you have been a great help. It turned to 30 degrees and snowed here in Ohio so we put the work on hold since I don't feel like blowing up the garage with the gas fumes etc. I did find the inertia switch and it has been tripped so we'll check that out first. All the fuses in the glove compartment are OK, unless the fuel pump fuse is somewhere else. Also I haven't located the relay yet. There is no power to the pump while turning over the engine or with just the key on. I guess I'll break down and buy a Hanes to look at the wiring diagram I'm sure I'll need it later.
 
Didn't read all the previous posts on this thread thoroughly, but don't forget the "nerf" switch. The inertia switch is located on the firewall near the clutch master cyl. They can appear OK, but be cruuded up inside and not allow current flow. Bypassing it is the quickest way to diagnose. Good Luck
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by wrenchinhand:
Ok. My E-Bay TR7 Spider arrived yesterday. I probably should have let Mark have the bid.
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<hr></blockquote>

Its not to late! =)
 
Weather warmed up today in Ohio so I'm back at the fuel problem. Spent most of the day sucking three years of sand out of the inside of the TR. I just can't believe people abandon cars like this. Anyway my discovery is as follows: Inertia switch bad. Someone has fubar'd it. So even if I jump it I still get no power to the 12V side at the fuel pump. What about the relay, what else does it control? I can't hear it clicking. I have wired the fuel pump direct and am supplying clean fuel to the injector rail, but still no go. The car runs for 20 seconds or so then runs out of fuel.
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I'm startin to drink now.
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Have you checked the fuel filter. Those silly Brit engineers put it after the fuel pump, so if it's clogged, not only does it slow/stop the flow of fuel, but if the flow is too slow, it can cause the pump to overheat and shut down. There's also a small screen in the pump (non-replacable) that can slow the flow.

If I'm reading the fuel injection wiring diagram right, the relay takes incoming battery power, a start input, and ignition input, and then sends power out to the inertial switch and ultimately the fuel pump. The white with green stripe wire on the relay is what supplies the juice to the inertial switch...pull the terminal off and use a 12 volt tester to see if it has juice with the key in the on position.

PS. If you want, I can scan and email you the full and fuel injection system wiring diagrams.
 
With the fuel pump hooked direct, pulling the line loose at the fuel rail I get a full line of fuel with plenty of pressure. So I don't believe it is a fuel filter problem. I get no power at the inertia switch with the key on or with the engine turning over. I still need to locate the relay and test it. I don't see it in the back of the glove box. All fuses have been test in the fuse box and are Ok.
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Have you checked your oil pressure sending unit and its wires? On tr8s(assuming tr7s to) no power will be sent to the fuel pump if this unit does not detect oil pressure. This gave me a heck of a headache a few years back and I had a bad sending unit.
 
I had a similar problem last year with my 81 EFI equipped car and I had both a bad inertia switch and bad combination relay. The relay actually has two built in, and in my case once I replaced the inertia switch I could hear one relay clicking, but the other remained dead. We ended up cutting open the relay and holding both relays closed and it started right up...which confirmed the relay was bad. Replaced it and knock on wood haven't had the problem again. When it quit (while driving) I ended up wiring the fuel pump into a radio lead to get it home...

Good luck...it will definitely be worth it when fixed...the EFI systems are great when running right!
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr> I get no power at the inertia switch with the key on or with the engine turning over. I still need to locate the relay and test it. I don't see it in the back of the glove box. <hr></blockquote>

Then you definitely need to find and test the relay. It is located behind (not in the back of) the glove box...it's about a 2x4" box with twin connectors on it. You may have to locate it by feel. If it were "missing" that would explain a lot.
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Halleluyah! Major breakthrough. Seems it was a sticking relay. However all the injectors are plugged. I cleaned two of them and got it running on two cylinders. So I know everthing is functioning. Now I need the time to pull all the injectors and either replace or try to clean them. I know... good luck. Eventually we'll have to replace them. Since I'm still assessing this car I'm not dumping to many $ into it yet. Thanks for all your help you've been great.
 
Awesome!!! And I have to agree with srmorse...when you finally get that FI system working properly, you'll love it. Since getting everything on mine straightened out last year, no problems, the car is "peppier", and best of all with gas prices being what they are, I'm getting 25+ mpg around town.
 
sometimes you can get the injectors rebuilt for a higher flow rate and increase the fuel rail pressure for higher performance. I paid $200 to have the injectors rebuilt for a higher flow rate on my rover intake manifold (that's for 8 injectors). Put an adjustable regulator on the fuel rail and a pressure guage and and you are ready for some experimenting.
 
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