5.3 vortec, fuel pump?

[philthyphil]

This is on a 1990, FJ62, with a 5.3 chevy vortec swap.

I think my fuel pump is dying, please help. I don't even know if the fuel pump is chevy or Toyota. Here is what happens:

It just dies whie driving. Usually after it has been driving a while. Then it won't start for about 20 mins. When it does, it's after me giving it some gas to help get fuel to the engine. If I only give it the 20 mins to sit, it only takes 5 mins of driving before it dies again. It just took me 3 hours to drive 15 miles. When it dies, it sounds like i'm running out of gas. It happened half way through the 500 mile trek home when I bought it a couple months ago, it seems to be steadily getting worse. At first I thought it was related to heat/overheating but the temp gauge reads normal and it doesn't seem be related, not that the aftermarket gauges are accurate. Please confirm or deny my hypothesis on this problem.

Last but not least, how many bananas to change a fuel pump? Breaking out the FSM right now to see if I can do this myself.

As always, any help is greatly appreciated.

 

[rover67]

take a look on the pass side rear frame rail, follow the fuel lines and see if you find the pump. It is probably above the rear axle.

Is it there?

It should be making a noticeable whine when it is running. See if it stops when the motor quits.

If it is the fuel pump, it is not too hard to replace assuming you get the same one.

are you in denver?

Also, the FSm won't help here, it's going to be a custom install that somebody did.

 

[philthyphil]

Rover, I am in Denver. I can hear it running. Anybody else got any ideas, what else could it be in if not the fuel pump?

 

[ntsqd]

Sounds like a form of vapor lock to me. That is caused by two things, hot fuel or high vacuum. Either one makes for a vapor that the pump can't pump. Is there a pump external to the tank? A 62 would have it's OE pump in the tank.

Inspect both the supply and the return lines for kinks, crimps etc., and too close to a heat source.
If an external pump, what is in the tank?
Clogged pick-up sock?
Loose hose clamp(s)?

 

[rover67]

ditto on the above post, is it an external pump or an in tank pump? If it is an external pump does the in tank pump run too or has it been deleted somehow? I failed to notice it was all in a 62 earlier.. sorry about that.

 

[Elbert]

you also might have a rusty fuel tank or trash in the fuel tank stopping up the pickup tube in the tank...

 

[kling-on]

Make sure there isnt a fuel filter BEFORE the pump it will make air bubbles and die ... replaced 4 pumps before I found out what was really wrong

 

[rover67]

Make sure there isnt a fuel filter BEFORE the pump it will make air bubbles and die ... replaced 4 pumps before I found out what was really wrong

Yeah, the wrong pre filter makes some of the more powerful inline pumps cavitate and even pull a vacuum in the filter housing. I fought the same thing for a while. too.

 

[philthyphil]

Thanks all, keep the ideas flowing.

The pump and filter are external. The work/engine swap was done for the previous owner by BTB in NV back in '05. I looked at their website today and found the exact pump and filter I have in their parts section $160 for both. I am thinking about just replacing both, to either solve the issue or eliminate it from the equation. I did have the pressure in the fuel system tested by a mechanic and they couldn't replicate the stalling but they did see a drastic pressure drop on the tank side leading them/me to believe it could be a pump issue. I don't know how to fix a vapor lock problem but hopefully it won't come to that. Mechanic says the pump may be getting too hot/burned up that's why it starts after 20 mins or so. The cool down period is what is really throwing me a curve ball.

Again, all ideas welcome to help educate me and let me drive the Yeti!

 

[phishincruisin]

I'm not sure I'd use that filter as a prefilter for the pump. I think one of the smaller style, like this Earls filter would be better. I run a filter like that before my walbro pump and the corvette fuel filter/regulator post pump. There was a recent thread about in tank vs inline fuel pumps on vortec swaps that might be good to check out.

 

[Elbert]

I run one of the earls type inline filter between the tank and pump, I run a GM fuel filter from a 99 SUV between the pump and the engine. Never had an issue from day one. I've swapped the primary filter once and up to this point I've never changed the smaller fuel filter. IN my view you should not run a super low micron count filter between the tank and pump. I just run the GM fuel filter becuase I know its a proven item and its easy to change and I can find one almost anywhere.

Hope I saying the micron reference right...my intent is to say that you don't want to run one of the super restrictive filters between the tank and pump. Most of the intank pumps only have a simple crude "sock" filter that filters the gas (pre-pump) and then you have the larger primary fuel filter out in line on the fuel line somewhere hopefully where its somewhat easy to change.

 

[rover67]

man, if you have a 62 fuel tank i'd be REAL tempted to put a decent in tank pump in it. It is already set up and ready to go for it. It'd work a lot better. You can buy a universal walbro from summit and throw it in there.

 

[philthyphil]

What is the advantage of a in tank pump vs. an inline? Inline seems better from an accessability standpoint.

 

[mwalls54]

The fuel will keep the pump cool in the tank

 

[ntsqd]

Fuel flows thru the pump (& it's motor) regardless of in the tank or not. There will be some convection cooling so long as the fuel level is high enough to surround the pump, but I'm not buying that the OE's did it purely for that reason. Think about it, 3/4 or more of the time the pump is at least partly not submerged in fuel because most are stood on end - not laid flat.

I think mfg assembly and noise were the main reasons that they did it. There are a lot of external mounted EFI pumps running around out there that work just fine.

For my own TPI swap I made the "pre-filter" because I couldn't get a coarse enough filter element for the housing that I wanted to use (I already owned it). As it happens I've a friend who works in filtration and he was able to supply me with some SS mesh. I built a strainer out of it and put that in the filter body. I don't really think of it as being a filter even though I tend to call it that. It is a strainer, it's purpose in life is to keep the big chunks out of the pumps. The other, after pump filters are for keeping the small stuff & water out of the injectors.

Something that is being danced around here, w/o being said - by me too, is that anything that restricts flow between the pump and the fuel in the tank by even a tiny bit will cause a pressure drop. If the pressure in the tank is ambient pressure, then any pressure drop takes you into vacuum. Boiling temperature for liquids decease with a decrease in pressure. Therefore vacuum in that section is not a good thing in the slightest. You can cause the fuel to boil at ambient temperature if you pull enough of a vacuum on it. I doubt that is going to happen in a truck's fuel system, but elevate the fuel temperature some and then pull a smaller vacuum on it and you've got a recipe for trouble.

If it is a 62 tank in the truck, what did they do for a pick-up? Without the pump in there things would be complicated. If the pump is in there, but not in use then simply applying power to it, w/o changing anything else, could solve the problem. If the pump is in there, then an external pump would have to be pulling thru it. That would be hard on the external pump, and as it prematurely ages could result in the symptoms that you have. If the 2 pump is there I would wire it in parallel with the external pump, or take the external pump out of the system and try using just the 62's pump if it's output pressure is high enough.

 

[rover67]

Good point on wiring the internal stock pump on if it is still in there...

I like the in tank pumps because the few inline external combinations suffered from cavitation due to the conditions that ntsqd posted.

 

[philthyphil]

I talked to BTB, the company that did the swap and they said they would have pulled the in tank pump because it couldn't keep up w/ the new engine. Right, wrong, or indifferent, it doesn't sound like its there for me to use. Ntsqd, what do you mean by "pickup"? It is a 62 tank on my 62, I am assuming, don't know why they would have swapped that.

 

[kling-on]

My pump is a 40-60'psi and I was told the stock FJ62 is more like 12-16 psi

 

[philthyphil]

BTB fuel pump for 5.3 vortec is 43 gph, mex pressure of 125 psi.

 

[philthyphil]

Anybody else have any ideas before I let this thread die?