MK1 Fuel Pump

[jmm39531]

I have an '85 MR2 and last summer my fuel pump stopped working. I took it to a shop and they replaced it for $700 total including labor. I also replaced the fuel filter right before taking it in. I have only driven the car a couple thousand miles since then, and I think the fuel pump is bad again. It is showing the exact same symptoms that it did last time it failed. The engine started intermittently sputtering one day, and then died. So my question is, how could my fuel pump go bad after 1 year and only a couple thousand miles? It sat in my garage for 4 months (Jan-Apr) and never was started or driven. But I put fuel stabilizer in the tank so I don't think that was the reason.
If I buy a fuel line pressure gauge and determine that it is in fact the fuel pump, I would like to try to replace or fix it myself this time. Can anybody tell me how hard it would be to remove the fuel tank and troubleshoot this problem.
Thanks for any help. If it turns out to be too much trouble, this may mean the end of the MR2 for me...

[LokiRx7]

Fuel pumps are really finicky, one day me and a friend returned three new pumps before we received an operating one. However once they are installed they are generally good for quite awhile. That doesnt rule the pump out completely though, I would check your AFM. That triggers the pump when you start the car, and if anything is malfunctioning in the AFM it will simulate a bad pump, or running out of gas.

There is a test procedure for the AFM, but Ill have to dig out my BGB to find it.

Also, there is a way to remove the pump without dropping the tank. It can get ugly and isnt reccomended by any means. The previous owner of one of my 2's performed this before I bought it. You have to cut a notch in the center floor/console area, Its hard to explain, again Ill need to post some pics up later. But it makes a fuel pump installation 1,000,000,000 times easier.

[mr2tim]

I even installed a bad new fuel pump from the parts store.

As Loki posted, test the pump before it goes in. dah..

I contemplated ripping the body under the shifter also but being so very close to the shifter mounting bolts etc. I was too freaked out.

Check these photos for reference later.

[jmm39531]

I checked the AFM according to my Haynes manual. It said to measure resistances across various terminals and they all checked out perfect.
I have spent the last couple hours looking at this problem and I am giving up now. If its the fuel pump like I think it is, there's no way I can fix it myself. And I'm not going to spend another $700 for another one. Goodbye MR2...

[1fastmr2]

JMM I will bet the repair shop did not use a factory DENSO fuel pump. I would ask the repair shop what the warranty is on the pump where did they buy the pump from. 700.00 is way over priced for this repair. The factory pump is only about 180.00. Sorry to read about your troubles.

Take care,
Phillip

[jmm39531]

The shop charged me $312 for the fuel pump. At the time I didn't know how much I should pay for one. And by the way they did a horrible job installing it. When I went to pick up the car, the battery was totally dead. And a few days later I noticed gas was leaking out. I had to take it back to another shop to get the leak fixed. The shop is 180 miles away so towing it back isn't an option.

1985 parts car is now for sale. I will post it in the for sale section shortly. It has a remanufactured engine with only 5000 miles on it...

[1fastmr2]

Where are you located?

[jmm39531]

MS gulf coast between New Orleans and Mobile AL.

[mr2tim]

Hold on dude, take a deep breath, walk away from the car and take a time out.

Sometimes I lose it when the problem is electrical too. This elect stuff ain't easy, but some small diagnostic steps will get you results!!

This system is more complicated than you think.

1. Do you have any computer codes in the computer?
Page FL-26 Service Manual

2. First off, fuel line 'pressure up" is controlled by at Vacuum Switching Valve (VSV) which inputs to the ECU...... Page 53 Elect Manual, Page FL-3 Service Manual
a. Without this input your electrically connected but there is no pressure in the fuel line.
b. (Toyota uses this to kill extry line pressure when you get off the throttle.)

3. The circuit opening relay attached near the ECU controls the power going to the fuel pump....see Page FL-111 to diagnose this relay.

4. Since you already checked the AFM then you unknowingly may have checked the Fuel Pump Switch inside the AFM. (you checked the Fc input)

Yes, it's not that easy but this is how it's done.

mr2tim

[LokiRx7]

It isnt that hard to drop the gas tank on the MR2, I can get it out in under twenty minutes anymore. Getting it out and back in is the hard part, changing the pump is easy. If you have any mechanical skill you can replace a fuel pump, dont let it freak you out.

In reference to my comment on dropping the tank in twenty minutes....

The very first time I dropped an MR2's tank it took me nearly four hours, mostly because I didnt have a repair manual and couldnt see some of the lines that were still attached to the tank. So take your time, and dont rush, its worth it!

[2restomod]

^Twenty minutes! That I'd like to see. Separating the flex filler hose takes me about that long . You might also want to just check the fuel pump without taking it out by jumping the pins in the code box.

[LokiRx7]

Originally Posted by 2restomod

^Twenty minutes! That I'd like to see. Separating the flex filler hose takes me about that long . You might also want to just check the fuel pump without taking it out by jumping the pins in the code box.

Well................ You see........... I totally replaced that

I used a flexible radiator hose, and a hose clamp. Before anyone says anything, it works great, and it was cheap! My old filler hose was so dry rotted it fell apart when I was taking it off of the tank. I made sure the clamp was easy to get to.

But the first time I dropped the tank that was one of the hardest parts, mostly because it was as hard as steel from age..... But my car sat in a field for five years too. That probably attributed to its advanced decay.

[2restomod]

^Well, that 'asplains it . Another trick is to leave the hoses on the tank and pull everything through the hole in the firewall instead of trying to get to all those damn small hoses and the fuel line. Take the intake fuel line off at the filter and take the vent assembly (whatever the hell that is) off the back of the firewall and feed it though the hole as you take the tank out. I also separate the fill tube from the back of the firewall so I can jiggle and pull that around to get the flex hose off the tank first. Still takes me an hour, but that's no reason to junk the car!

[LokiRx7]

Originally Posted by 2restomod

^Well, that 'asplains it . Another trick is to leave the hoses on the tank and pull everything through the hole in the firewall instead of trying to get to all those damn small hoses and the fuel line. Take the intake fuel line off at the filter and take the vent assembly (whatever the hell that is) off the back of the firewall and feed it though the hole as you take the tank out. I also separate the fill tube from the back of the firewall so I can jiggle and pull that around to get the flex hose off the tank first. Still takes me an hour, but that's no reason to junk the car!

Yeah, that way you dont spend thirty minutes trying to stick your hand in that tiny space at the back of the tank to slip all those tiny hoses on. I really messed up my hand doing that too!

[muffinman]

jmm39531
the fuel pump is not that hard to change , i also dreaded changing it but as others have said it's not that bad. before you get rid of the car at least atempt it and if you can't do it then give up but you'll see it's tricky but not impossible just take your time.

[jmm39531]

I am very embarrassed to report that it was not the fuel pump like I thought. My distributor cap had somehow worked its way loose. I simply retightened it and the car is running good as new now. I spent all those hours underneath the car and was looking in the wrong place. I'm not a very good mechanic...

[LokiRx7]

Originally Posted by jmm39531

I am very embarrassed to report that it was not the fuel pump like I thought. My distributor cap had somehow worked its way loose. I simply retightened it and the car is running good as new now. I spent all those hours underneath the car and was looking in the wrong place. I'm not a very good mechanic...

Thats quite all right even mechanics have those moments. I took my coil wire off of the distributor when I replaced the axles, that way the car wouldnt start up for any odd reason while I was under the car. I spent an entire day trying to figure out why I wasnt getting spark, the way I layed the wire down it almost looked like it was still connected!

Dont let it discourage you, this is simply how you learn with nobody to teach you, trail and error!

I hope you have fun with your MR2, god knows I have!

[2restomod]

Doh! Congrats though on solving the problem. And look at all the great info you got for the next time you need to change your fuel pump!

[mr2tim]

I was raised by hoseheads outside Detroit, Michigan and was warned when I was a kid not to mix Radiator and Gas Hoses.

Radiator hose will break down incredibly fast in a gasoline environment.? (Changing the fuel filter yearly- might - stave off breakdown particles.)

I hesitate to think of the fuel injector cleaner!

(Notice when at the parts shop that the Rad hose is $10.00 and the fuel hose $40.00, this should be your first big clue?)

By the way, here in South Florida ya can't buy these 20 year old hoses.

Any hose stories out thar?

[LokiRx7]

Originally Posted by mr2tim

I was raised by hoseheads outside Detroit, Michigan and was warned when I was a kid not to mix Radiator and Gas Hoses.

Radiator hose will break down incredibly fast in a gasoline environment.? (Changing the fuel filter yearly- might - stave off breakdown particles.)

I hesitate to think of the fuel injector cleaner!

(Notice when at the parts shop that the Rad hose is $10.00 and the fuel hose $40.00, this should be your first big clue?)

By the way, here in South Florida ya can't buy these 20 year old hoses.

Any hose stories out thar?

First off there is a reason that fuel line hoses are more expensive. They are designed to withstand much greater pressures than a radiator hose. I am using a radiator hose as a filler neck hose. It isnt experiencing any pressure at all. So changing the fuel filter wont affect the filler neck hose at all. I am sure it has fuel splashing in it and sitting in it from time to time, but it hasnt prematurely failed.

The hose has been there for nearly two years, Toyota cant order me a filler neck hose, neither can any auto parts store in the land. I am sure there are better options, but I havent had any trouble with it, and as cheap as it is I wouldnt care if it failed tommorow, I would replace it with the same thing.

I also dont beleive in injector cleaners 99.9% of them dont do a thing, I certainly dont run it through the gas tank. If my injectors need cleaned I pull them out and drive down the street so a buddy of mine can clean and balance them, which I try to do annually anyway. (and no I dont get a 'buddy' discount either....)