I thought I had a bad fuel pump, but now I have no idea what is wrong.

Not sure why this thead was linked at the bottom of another thread but here is the final update, albeit 3 years late.



A month after changing the plugs, my car started the intemittent bogging, etc again and finally threw a CEL, which was the one for fuel. I took it back to the mechanic who found the bad plug, expecting to have him say the fuel pump was bad. He actually put a fuel pressure gauge on the car and taped it to the windshield so he could see if the pressure was dropping. The pressure read what it was supposed to but it started to buck and surge and again tossed a CEL for fuel system. The O2 sensor is part of the fuel system CEL too, so he took a good look at mine. Pulled it out and it looked fine but then he got a closer look at the wires and one was worn right through the insulation and when I'd accelerate, it was touching the front motor mount and grounding out. :hairpull



Put in a new O2 sensor and the car ran the best it had in a long time...but by then, I had already bought my Dad's Mazda 626 (which lately has turned into a real money pit) and rarely drove the Accord and ended up selling it.
 
160K on an O2 sensor is, as the English would say, mad mate!:eek::)

I know a guy who changes his every major tune up at 30k just to get that quick response a new one has and to check the cable running from it which on all cars is pretty exposed.



Bet that Honda would have gone on to 300k with little else wrong with it :) with the same fuel pump too!
 
J.J. said:
How many miles are on the 626? Just curious!
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Almost 155,000.



I think a lot of the problems I have been having with it can be traced to the coolant tanks, which are pressurized on the '98 and newer V6 626's. They contantly develop leaks (replaced 3 in 3 years) and always in the exact spot. Then hot coolant leaks on the alternator, a/c compressor and the drive belts. The alternator has been replaced twice, the a/c compressor once and the crankshaft pulley came apart on me.



Mazda is no help at all with the problem, other than replacing the last tank for free because it was less than a year old. No headway in convincing them the accessory side of the engine is being ruined by the cheap design of the coolant tank.
 
Have you thought about an aftermarket tank? It doesn't have to be one necessarily built for the Mazda 626 but one that is similar maybe.



Mercedes had a problem in their 300E's and 190E's with the necks of the radiator at the upper hose breaking because it was made out of plastic and would fail over time usually when you were very far from home. They finally figured out that the necks had to be reinforced with steel tubing.
 
No one makes an aftermarket version that I've been able to find. The last 626 was made in 2002, seems that Mazda really doesn't give a crap about them anymore.
 
Sounds like a good excuse for a new ride, Scott :D



But seriously, if you are spending money time and time again to fix your 626, it might just be cheaper to jump into another ride for the time being. Sometimes, cars just have to be let go =(
 
I would get an aftermarket stainless steel expansion tank with a cap and dump the mazda one. Find a way to mount it, they usually are tubular with the nipples at the bottom and made in different lengths for hot rods. Worth it considering the amount of collateral damage its costing you.

Oh and also get a transmission cooler for that tranny if its an Auto, Mazda sedans are notorious for dying transmissions around 200k because they don't have conventional tranny coolers like others. Ford parts bin I guess :(



Or just get rid of it before it comes looking for your wallet again :)
 
Scott.. I think it is time to treat yourself to a brand new vehicle.. God knows you have earned it! :hifive:
 
Yal said:
I would get an aftermarket stainless steel expansion tank with a cap and dump the mazda one. Find a way to mount it, they usually are tubular with the nipples at the bottom and made in different lengths for hot rods. Worth it considering the amount of collateral damage its costing you.
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Good idea, I'll have to look around. I still have one of the old ones, so I might be able to have one made to fit.



Oh and also get a transmission cooler for that tranny if its an Auto, Mazda sedans are notorious for dying transmissions around 200k because they don't have conventional tranny coolers like others. Ford parts bin I guess :(



Or just get rid of it before it comes looking for your wallet again :)
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My car has the V6 and 4EAT transmission which apparently is pretty trouble free, according to a Mazda 626 board. The 4 cylinders on the other hand....first recommendation they make to anyone who has one is to get an auxilary tranmission cooler.



DaGonz-a new vehicle this summer was the plan but more than two months of nearly non-stop rain (20+" since May 1st) has put that on hold. I am way, way down vs last year now. :(
 
I had a 96 2.5L V-6 five speed and it was the most fun to drive car I've yet owned. After "tinkering" with it a bit I could spank a 5.0 Mustang up to 80 MPH then watch them walk away. On the down side it was a BEAR to maintain. With 40+ vacuum lines and scads of sensors, constant replacement of seals to keep oil off of the spark plugs, and so forth I had to sell it cause it was eating me up. The requirement for premium fuel didn't help either.



Maybe you could swing a 2nd hand Honda deal? Yes, I am aware of the torrential rains/flooding you have been going through up there but you've got to have a reliable economical car to work from.
 
RTexasF said:
Maybe you could swing a 2nd hand Honda deal? Yes, I am aware of the torrential rains/flooding you have been going through up there but you've got to have a reliable economical car to work from.
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very good point. Scott I'd recommend getting a ful diagnostic of your engine as it may open your eyes to other potential problems that will affect you in the future. Have your mechanic do a leakdown test for you.



I'm shocked that the crankshaft pulley came apart..that's nuts!



Anyways good luck with your car troubles and I hope the rain clears out for you.
 
kaval said:
very good point. Scott I'd recommend getting a ful diagnostic of your engine as it may open your eyes to other potential problems that will affect you in the future. Have your mechanic do a leakdown test for you.



I'm shocked that the crankshaft pulley came apart..that's nuts!



Anyways good luck with your car troubles and I hope the rain clears out for you.
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The engine on those cars is the most reliable part from what I understand...provided you change the oil and filter regularly. I've been running synthetic motor oil in it since I bought it. It is the other stuff that gets to me and I think that stupid overflow tanks has a lot to do with it. Not to mention the crappy leather (my driver's seat needs to have the leather replaced) and my headliner is coming down in back now. Plus...for some reason the weather strip around the door openings isn't pressed into a groove, it is glued on and every summer, the adhesive gets gooey and the weather strips pull away from the body of the car.



Real shame that Mazda wraps a great engine and decent handling with a car that isn't in the same league. The main reason I bought the car is that my brother has had several and never had a problem with them. He put 215,000 miles on his '87 626 GT (turbo) and the original engine, transmission and turbo were all in great shape when he sold the car. Other than tune-ups and brakes, the only other thing he did to it was a clutch at 160,000 miles.
 
Yeah, I'm afraid that the more that Ford has gotten involved with Mazda, the worse off Mazdas have gotten. Our '95 Millennia wasn't much of anything but trouble. Had a nice sporty feel for being a fat 626. But there were so few of them out there that help in the form of forums and enthusiast boards were few and far between.



The day we sold that car I danced a jig.
 
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