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View Full Version : These cars do the ****edest thing...



ObiRichKanobi
03-13-2012, 09:36 PM
My driving season ended rather early and abruptly last year when my F/I TR7 suddenly died after taking a turn, and had to get flatbedded home. Being a F/I TR7, the electric fuel pump wasn't working. The pump was some after market one, and the air flow meter had been jumpered so that the pump energized all the time the ignition switch was on (not to OEM specs). So...no power to the pump. Spent a couple hours checking things out...inertia switch...check. Combined relay...check. Fuel pump...dead. Well, a short time after that my dad passed away, and I kind of lost my ambition to work on it, so she's been up on jackstands in the garage all winter.

Fast forward about 5 months. Weather's getting nice, so figured it's time to see if I could track things down. Checked the inertia switch again...check. Power coming off it...check... but only when cranking (hmmmm, the Air Flow meter had been jumpered and so should have power anytime the ignition was on). Pump dead. So...I had a used OEM pump, so decided to just swap it in. Still dead when just in the on position. Then I turn key, and wala...she starts and runs! That was the good news. The bad news was the used pump has a serious leak, so had to shut her down. Ordered a new pump yesterday.

So...all of a sudden the electrics (that had been modified by a PO) started working the way they are supposed to, but only with an OEM pump. Very strange...but happy I was able to trace it down without having to tow her to a shop.

BRSLimited
03-13-2012, 10:29 PM
Wow Lucas fixing itself? Now that is unheard of.

tomshobby
03-13-2012, 10:49 PM
Wow Lucas fixing itself? Now that is unheard of.

Probably Lucas way of postponing failure until on some far-out back road.

DNK
03-13-2012, 11:15 PM
Rich- Does the fuely 7's inertia and fuel pump run thru the oil switch?

ObiRichKanobi
03-14-2012, 05:42 AM
Rich- Does the fuely 7's inertia and fuel pump run thru the oil switch?

I don't think so. Don't remember seeing that on the wiring diagram.

DanB
03-14-2012, 08:16 PM
By replacing the fuel pump with the OEM, you must have injected just enough Lucas Smoke back into the system.

ObiRichKanobi
03-14-2012, 09:00 PM
Funny though...the fuel injection system is Bosch! Never thought that Lucas smoke being low would affect it.

DanB
03-14-2012, 09:12 PM
I have heard that Robert Bosch was Sir Lucas's illegitimate brother....

Dale
03-14-2012, 09:15 PM
Glad you got it going, Rich. I'm still suspicious of the relays in front of the glove box. When mine quit, the car would run ie: the fuel pump would operate, but only so long as it was cranking. If yours continues to run, it makes me think that somthing is bypassed. If the relays are working they should switch power from the cranking circuit to the pump via an indication from the air flow meter. You are correct of course about the FI being Bosch and extremely reliable, though subject to electrical gremlins due to age. My old 7 sits outside and I only needed to drive it to work a couple times this winter, but it fires right off and idles stone cold after sitting for weeks. Sure wish my
J-H had it.

Dale
03-14-2012, 09:19 PM
Another thought, Rich. I'm pretty sure that the fuel pump should not operate when the key is just on. It should only operate when cranking or when the engine is running.

ObiRichKanobi
03-14-2012, 10:08 PM
Another thought, Rich. I'm pretty sure that the fuel pump should not operate when the key is just on. It should only operate when cranking or when the engine is running.

You're right...before the "incident" mine ran anytime the key was on. I'd had my "mentor" check it out once and he said that the switch in the air flow meter was jumpered so the relay always "thought" that the car was running. Now it runs the way it was designed - when cranking, and then it keeps running when the car is running. But like I said, the after market pump wouldn't work, but the OEM one would. Just really strange.

TR3driver
03-14-2012, 10:25 PM
I have heard that Robert Bosch was Sir Lucas's illegitimate brother....

Good one! And it explains SOO much!

DNK
03-14-2012, 11:43 PM
My Wedge the fuel pumps cycles when turned to run