The AM Forum

I have the Bed off my pick up truck to do stainless steel brake lines and a complete brake rebuild after 140K miles. I figured it a good time to replace the fuel pump. It takes about 15 minutes with the bed off. Last night my Son and I dropped in a new AC Delco that worked fine. This morning I was giving the old one a good look trying to decide if I should toss it or keep it and noticed one of the two leads to the pump motor had melted insulation. This was inside the tank up top where the fumes hang out. I've been told it is a good idea to have plenty of fuel in the tank when it is hot outside to keep the pump cool but never heard of one catching fire.
Now I think I will rip it apart to see what's inside save the 3- 1/4 inch Stainless steel support rods then deep six it.

Great.  Nothing like living dangerously.

Just think, you could be standing next to your charred truck trying to convince the police that you aren't a member of the mob and don't know anything about a hit!  :)

Because of my line of work, I am dealing with modern fuel pumps on a daily basis.  I am not sure what type of pump yours is. That being said, Most modern pumps (georotor,type) will have damage/die within 12 seconds of running without fuel.  Yes, 12 seconds is the spec.  The fuel is the lubricant and coolant for the pump. 

Yes, I used to do noise suppression work on GM fuel pumps, and they DO need to be in gasoline for cooling.

One way to keep an eye on fuel pumps is do a current draw test with a known good pump.

If the current draw changes more than 8-10% it's time to change.

Worn pumps usually draw less current.

If the truck has enough fuel to move there's little chance of ignition within the tank. The mixture will be too rich.

Running around on E is asking for problems with pump cavitation and lack of lubrication on some models.

A melted connector may be a chemical reaction. 

So if someone is about to run out of gas, the pump is cooked if they don't power down within 12 seconds & coast?
Nice.

I'm not in the habit of running on fumes by any means, but that's the second "modern" maintenance issue that can be costly if ignored.

The other is to not change the brake fluid every few years.  With ABS, it would be more than just a few wheel cylinders & seals in the master to have to replace because of contamination & rust.

I usually never run below 1/4 tank. I've run that tank low maybe 3 times in 140k miles. I still think pumps in tanks is a dumb idea. It wasn't a chemical reaction the wire looks like it melted the insulation. Maybe a poor connection in the connector since it was up near the top.
Hopefully back  on the road in the next couple days.
Today we mixed tar with a little heating oil and coated the rear frame and underside of the bed with a nice thick coat of roofing tar. Cheap and much more effective than the crap in spray cans.
Stainless steel brake lines are great. I'll be doing transmission cooling lines next for only $80 from Classic Tube. Steel is $60 so a no brainer choice.

I agree that in tank fuel pumps are a bad idea, when they were mounted on the block it was a half an hour and $30 to replace one. a couple of months ago I had one replaced (no place to work on my truck) it was over $600 for pump and labour. 

Absolutely!  I have a sand blast system that uses two hoses - air and material.  I had a second gun that I used for crankcase drainings.  I would hook up the "rust proofing" gun and press the trigger - out came a fine spray that had considerable force (90 PSI).  It would blow off the road crap and replace it with a coating of oil.  Better in my opinion than brushing, perhaps, because it would apply the oil with force.  Anyway, it worked.  My after 11 years 67 chev truck was rust free any where I applied the oil. The places I missed were very rusty.

Up to a point the other gun was used to  clean the rust off without removing the good metal and prepare the surface for some fiberglass and epoxy.  Those patches never came off.

Al

I guess I gotta disagree with that  ;D  Electric fuel pumps (with associated fuel injection and computer-controlled mixture/spark) have resulted in a HUGE leap forward in vehicle reliability.  A newer vehicle now starts EVERY time, no matter how cold or hot.  No more vapor lock, no more cranking the engine for 20 seconds when it's cold to get the fuel to fill the carb bowl (and by that time, when it's -20 degrees, you've worn down the battery), no fiddling with stuck chokes, and no driveability issues.  Vapor lock was a big problem back in the day, or particularly with older cars using the newer gas, with the fuel pump mounted on the hot engine.  No more of that nonsense at all anymore!

While replacing a tank-mounted fuel pump may be a PITA, it's my experience they seldom need replacement.  For some reason Chevy trucks are prone to fuel pumps going bad, seems like at 100K-150K you'll be looking at a new one.  I've run other cars to 250K with no fuel pump issues.  But I think I've replaced fuel pumps on most of the carbureted cars I had, and I've also seen cars where the cam lobe was worn enough that it wouldn't jog the fuel pump.  Solution there was either an external electric pump or replace the cam. 

More expensive to replace?  Perhaps, but I'm betting it would be at least $200 to replace an old-style fuel pump nowadays at a garage.  And the improvement in reliability is considerable.

John, I agree with you on the system I just don't like the way the fuel pump was installed inside the tank. I would prefer it outside the tank. It was very easy to replace with the bed removed. AC delco cost me $330. Cheap ones run about $270.
My gas gauge sender had an open when the tank was full so decided to change the whole thing. Almost 12 years old so didn't owe me anything.
Al, I need to design a gun to get into the tight spots. Drain oil is quite sloppy.
Roofing tar with a little heating oil the thin it out worked great. This morning it is well dried but still soft. I did the rear wheel wells a few years ago which still looked great.   

Fuel injection requires either a booster pump within the tank, the whole pump in the tank or a gravity fed pump under the tank.

I'm with Johnny. The old pumps could leak gasoline all over the landscape when they went bad. You could wind up paying big money if your ride leaks whilst parked the wrong place.

Carbonators are nothing but a toilet bowl atop yer engine. Engine life and fuel economy is directly related to a well calibrated fuel system.

Some in tank pumps are pump, gauge electronics and other gizmos all in one package. These can cost hundreds of dollars. Some Jeep pumps are upwards of $600.00. Ouch. 

Today's gasoline is awful, with water-related problems caused by the ethanol, especially for vintage cars like I've got that sit around for months at a time.

Early fuel injection and high pressure fuel pumps were more problematic than a basic cam driven fuel pump and carburetor.  I had a 1973 Volvo 1800ES that I converted to a 2Bbl downdraft Weber because the Bosch Jetronic system was awful.    Put an electric bellows pump on there and was done with it.

Tried to keep it stock, but from the injectors to the sensors that controlled the injectors, to the solid state "brain" that caluculated what it could, it was a never-ending shell game to reveal which component had the latest problem.

Meantime, give me the sweet sound of a set of Mikuni-Solex sidedrafts with velocity stacks on a Datsun 2000 overhead cam convertible.  Yeha!

Even the Hitachi/SU's in my Datsun1600 OHV are a pleasure to work on, and they don't need much work with a UniSyn and a wrench to synch the linkages.

Fuel pump, cam driven off the side of the engine, is about $40 new, or a rebuild kit for about $12.  Unfortunately, it's been difficult to find alcohol-resistant rubber to deal with the ethanol...

I can't disagree that the new systems start first time, every time; regardless of WX conditions, the political climate or the wife's attitude. But, I can't fix the darn things. I drive a '93 Dodge Dakota with a 3.9L V-6 with EFI. Starts and runs great, but the day the FI system dies, it's down at the shop.

I'm looking for a completely pre-computer Chevy 3/4T, preferably with a 292 I-6, 1-bbl carb and a 4-speed manual truck box. To prevent vapor lock, just mount an inline electric pusher pump back by the tank. No worries. If I can find that truck, I can keep it running with bubble gum and baling wire.

Everything's a compromise. You just gotta pick your priorities and go with 'em.

You got almost the same truck I do, mine's a 91 Ddakota that also has that 3.9 V6. Nice motor, basically a Mopar 318 V8 with 2 cylinders removed. They titled it a 92, but the door tag gives the date of manufacture as 8-91, plus it has throttle body injection, not multiport, which would've been on 92 and later. 1991 was the last year for a throttle body on those things. This spring I was having problems with it, drove it a few miles, shut it down for a few minutes, went to fire it up and it would die as soon as I let off the key. Managed to get it running enough to limp home. First thing I figured it was, and everyone was telling me had to be going bad, was the fuel pump. Great. So I dig out the Haynes repair manual that I had for it, and start looking into the problem. Checked everything related to the pump, all was good. Said in the book to take off the gas cap and put your ear to the hole as the key was on and listen for the pump. It was running fine. So I let the truck sit for a while. Came back later and it started fine. Well, the thing was due for inspection, so when I took it to the shop, I told my mechanic what it was doing. He told me it sounded like the idle air speed motor was built up with carbon. That IAS motor sits inside the throttle body, so he said when he was inspecting it he would take the throttle body apart and take a look at that motor. Sure enough it was corked up, so I guess it fixed it, I haven't had any problems since.

Yeah, I like the engine. I put a new one in mine at about 185K. The previous owner (I'm the second owner) had overheated it at some point and the Al heads both cracked finally. Rebuild shop told me that's a common occurence with that mill. Friends were asking me why I put a new engine in "that old beater". Told 'em, "Well, I paid a grand for it about seven years ago, so it's paid for. And when the new engine is in it, it's still paid for. Plus, I like driving it."

So, it's got a new engine and a new radiator. Runs great and gets about 20 on the road. If the tranny goes out, I'll rebuild that too. And it'll still be paid for. That's pretty reassuring about now.

I get around 19 out of mine most of the time. I'm the second owner of it, the first owner was my great-grandfather, when he died the truck was given to me with only about 33k miles on it.

Nice to know I'm getting about the average on mileage. Until the new engine broke-in, I was getting about 15 and was getting a little concerned. I don't drive that much. Ten mile round trip to work and and back since I moved ( three mile RT before that), so it took a while for it to come in, but when it did the mileage went up from 14.5 to 20 in the space of one fillup, which I do weekly. A very pleasant surprise. But it's running great and I can live with 20.

Yea, I have a lot of hills around here. Is yours four wheel drive or two wheel? I think the 2wd models did get a little better fuel mileage becasue they would be a little lighter.

2WD I stay home if the WX is too bad. Only stayed home once so far.
CT isn't all that bad for getting around in the winter. I don't drive off road.
I like a simple truck to haul stuff. This one hauled a lot of building materials.
Bed went back on last night and hope to test drive it later today.

That's why I like my 4WD. Only ever had to use it once, and that was to get it out of its parking spot, had it on some bare dirt, then it rained and turned that bare patch into a mudhole.

You haven't been stuck untill you've been stuck with 4WD.

Ask the man who owns one.


klc

You must be one of the "invincable soccer moms"  ;D  ;D  ;D

That's when you need a good wench! ;D

Frank,
My brother had a Buick that suffered a fuel pump failure several years ago. Rather than have someone else replace it, he did it himself.  He dropped the tank and replaced the pump to find out that the wires leading into the pump were burnt much the same way as yours.  It was an internal pump too.  A pretty stupid idea if you ask me.  But he put it all together and dumped the car after that. He didn't want anything to do with it. I gave up driving GM products for stupid engineering many years ago.

What size fuse is there to supply enough current to melt insulation?
Late model cars sometimes use environmentally friendly wire insulation.
The stuff does not hold up to hydrocarbons.

Dave it looks like #18 and not a chemical reaction. It was up by the connector so maybe there is a bad chrimp in the connector insert.
I didn't tear it down yet but got the truck back on the road tonight.
The fresh coat of tar under the bed and frame looks sweet.

Shelby, mine's 2WD. I'd like a 4X4, but the price on this one was too good to pass up, and my old Gutless Cutlass was in the process of going paws up at the time. I lived for about 20 years in the Sierra Nevadas near Yosemite and drove 4X4s all that time. The old joke is that four-wheel-drive is only good for getting you stuck in places a tow truck can't get to, but with good tires and decent driving technique, they'll do very well. I had 50's era Jeeps, two different 1T military Power Wagons and a full-time 4WD Jeep Cherokee. The old Jeeps were the most fun, the militarys were the workhorses and, overall, the Cherokee was the most practical. There's definitely a difference in fuel consumption with a four-by, just from turning all that extra stuff in the driveline.

IMHO the Dakota was one of the best pickups ever.  The bed was the right size but it was smaller, got better gas mileage, and was more maneuverable than a full-size.  I bought one new in 1989, a 4X4 Dakota Sport with the 5-speed manual.  I took it to Kenya where it endured mostly off-road (even when you're on-road in Africa, you're off-road!) and then on to my posting in the Philippines.   Despite the fact that it got the hell beat out of it in Africa and endured the stifling heat and humidity (while generally idling in horrendous traffic) in the Philippines, it never let me down and sometimes ended up rescuing lesser vehicles that couldn't take the punishment.

I sold it in the Philippines in 1995 for $1000 less than I paid for it.  Of course, the ONLY thing that broke was 1 week after I got the deposit from the buyer the A/C evaporator sprung a leak.   The Manila Chrysler dealer wanted $700 and a week to fix it (in a country where labor was about $2/hour).  Looking at the service manual it didn't seem that hard.  My maid and I pulled the dashboard, replaced the evaporator, and had it back together in 4 hours.  The hardest part was getting the shifter console out!

I really miss that truck, although I gotta say my subsequent '78 F-150 and '94 Chevy K1500 were/are pretty decent trucks too - but neither began to approach the gas mileage and agility of the Dakota.

hey maybe it's one of them fusible links

John,
My brother is driving a '98 or '99 Dakota. It has about 200k miles on the factory clutch. I think he has a V6 in it. The only issues he has had is rotted brake lines a couple years ago anf the deer who ran into him on Thanksgiving day about 6 years ago. It just told me he thinks it needs front wheel bearings.
I would think the pump has a real fuse. I am sure the insulation is melted but up near the connector. The rest of the 8 inch run is fine.
Drove it to work this morning so all is well.

I had to replace the brake lines on my Dakota too. Too bad they don't make them anymore, they were a nice truck. Aother granddad of mine has 2 of them, one's a 2006 with a 4.7 V8, and the other is either a 1997 or 98 with a 318. The older one has been beat around but still keeps going.