New Fuel Pump, New Problem...

Joined
Jun 24, 2013
Messages
55
Location
Clark, Colorado
After getting tons of useful tips here, and installing new, old stock OEM FP, a new strange problem occurred today, which I can't quite figure out. I'll explain: after finally getting the arm that actuates the diaphragm to move, I installed the pump, primed the system by putting a little gas down the carb, fired it up. It started on the first crank, something it hadn't ever done before, especially in winter. The average temp these days is around 18-25 F in the day, dropping to zero, or close to it, at night. So, I live 12 miles from from the nearest town, on a farm. The road to town is narrow and has no shoulder, so it's really a drag to have your truck just stop dead.

Well, I decided to drive into town. I was impressed with the way the engine seemed to respond quickly when accelerating. About 2 miles from destination, running about 45mph, the truck started to lose power. It didn't shut down like it did when the pump failed, but it slowed down, and I downshifted to 3rd. Up ahead I saw a place to turn around. I slowed down, turned off the road, out it in neutral. It idled fine at about 550rpm. I turned around, pulled out, made it home okay. It didn't do it again, until I was about 100 yards from our place.

I left it running, opened the hood, there was gas in the filter, gas in the glass on the carb. None of the numerous vacuum hoses look to be disconnected or cracked. I shout it off, started it again about 4 hours later. It started right up on the 1st crank. I looked in Haynes manual, and quickly found all sorts of possible culprits: points, spark plug wires, vacuum advance, fuel hoses, etc. I'm wondering if anyone can tell by my explanation what the problem may be. I'm wondering if it might be the high speed jets in carb, and perhaps if running carb cleaner might fix it. I'm not wanting to disassemble to carb as I don't have a heated garage. One thing I noticed is that the new fuel filter is only about 1/3 full, below the paper element, and when the engine is running, it seems like there are little air bubbles inside, right where the line to the carb is. In all my years of having this truck, it's never behaved like this before. Could the new pump somehow be bad? Could this be the beginning of a cascade of problems that are appearing now that the fuel pump is running at increased pressure? I have a lot of questions, and I'm sure some of you probably have a better idea of whats going on than I do.
 
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All I can think of is a partially blocked jet or the vacuum secondaries not working. needle could be sticking in the seat intermittently. Sounds like a carb clean would be a good idea. make sure the main port on the pump [lowest] is going to the carb and not the return line.
The filter is normal when half full, thats how mine looks.
Do you have an electronic distributor? Mine behaved like that when the distributor was wired wrong.
 
Last edited:

OSS

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New fuel pumps are still available. I'm wondering if your NOS pump arm is sticking since you had to wrestle with it to make it move prior to the install. The camshaft presses the arm inward, but it's the spring pressure inside the pump that makes the arm return. If the arm was sticking, the cam could easily push it in, but maybe the spring was having trouble returning it. --- m a y b e.

Was the engine running ok before the NOS pump was installed?

When a running engine is losing power, that's usually cuz it's not getting enough fuel.

So either:
The inlet pipe in the tank has something intermittently blocking it, the fuel filter looks clean but actually is restricting flow, the fuel pump is malfunctioning, or debris got into the carb when the pump was changed (not uncommon).
 

NeverGiveUpYota

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When you changed the fuel pump did you change the filter? I second you’ve shaken up junk and sent it moving along the fuel lines.
Change out the filter but as you do blow air down the lines before the filter back to the tank just to air on the side of caution. I used a 60cc syringe to do mine.

Also you can do an okie rebuild to the carb to help suck debrie out although your saying your sight window is correct. But basically w/ the top of the air cleaner off, have a square of cardboard w/ a hole in the middle for the bolt (or take the bolt out), have the truck running not on choke, pull the throttle linkage up to 2k ish as you bring the cardboard down and suffocate the air horn on the carb till it stalls out. Try that a handful of times. It’s a cheapy way to clean out crud before a cloud billowing seafoam to the carb. You can also pull the air horn off and take out the two long jets (as well as the main jets) and careful feed thin wire inside and spray out w/ carb cleaner.
 

ToyotaMatt

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After getting tons of useful tips here, and installing new, old stock OEM FP, a new strange problem occurred today, which I can't quite figure out. I'll explain: after finally getting the arm that actuates the diaphragm to move, I installed the pump, primed the system by putting a little gas down the carb, fired it up. It started on the first crank, something it hadn't ever done before, especially in winter. The average temp these days is around 18-25 F in the day, dropping to zero, or close to it, at night. So, I live 12 miles from from the nearest town, on a farm. The road to town is narrow and has no shoulder, so it's really a drag to have your truck just stop dead.

Well, I decided to drive into town. I was impressed with the way the engine seemed to respond quickly when accelerating. About 2 miles from destination, running about 45mph, the truck started to lose power. It didn't shut down like it did when the pump failed, but it slowed down, and I downshifted to 3rd. Up ahead I saw a place to turn around. I slowed down, turned off the road, out it in neutral. It idled fine at about 550rpm. I turned around, pulled out, made it home okay. It didn't do it again, until I was about 100 yards from our place.

I left it running, opened the hood, there was gas in the filter, gas in the glass on the carb. None of the numerous vacuum hoses look to be disconnected or cracked. I shout it off, started it again about 4 hours later. It started right up on the 1st crank. I looked in Haynes manual, and quickly found all sorts of possible culprits: points, spark plug wires, vacuum advance, fuel hoses, etc. I'm wondering if anyone can tell by my explanation what the problem may be. I'm wondering if it might be the high speed jets in carb, and perhaps if running carb cleaner might fix it. I'm not wanting to disassemble to carb as I don't have a heated garage. One thing I noticed is that the new fuel filter is only about 1/3 full, below the paper element, and when the engine is running, it seems like there are little air bubbles inside, right where the line to the carb is. In all my years of having this truck, it's never behaved like this before. Could the new pump somehow be bad? Could this be the beginning of a cascade of problems that are appearing now that the fuel pump is running at increased pressure? I have a lot of questions, and I'm sure some of you probably have a better idea of whats going on than I do.

U disturbed The Supply Line going from Pump to carb , while installing the NOS pump , This loosened up a bunch of small debris from inside wall of metal and or rubber line / combination of both , this may have clogged your primary & or secondary jets or both .

Did U replace the small rubber supply line from pump to the metal supply line just above pump to the carb ?
or
re-use the old one ?
 
Joined
Jun 24, 2013
Messages
55
Location
Clark, Colorado
Thanks for the reply.. I used the old one, and what you mentioned is probably what happened. I've noticed that today, even in the 20 degree temps, it starts right up, and runs just fine. I'm going to parts store today and will try to get some fuel hose.
 
Joined
Jun 24, 2013
Messages
55
Location
Clark, Colorado
New fuel pumps are still available. I'm wondering if your NOS pump arm is sticking since you had to wrestle with it to make it move prior to the install. The camshaft presses the arm inward, but it's the spring pressure inside the pump that makes the arm return. If the arm was sticking, the cam could easily push it in, but maybe the spring was having trouble returning it. --- m a y b e.

Was the engine running ok before the NOS pump was installed?

When a running engine is losing power, that's usually cuz it's not getting enough fuel.

So either:
The inlet pipe in the tank has something intermittently blocking it, the fuel filter looks clean but actually is restricting flow, the fuel pump is malfunctioning, or debris got into the carb when the pump was changed (not uncommon).
It was running fine before the fp went out. Never had any issues in the last 10 years at all. I think you're probably right about dislodging dirt when I pulled off the fuel line hoses. I'm wondering if running b-12 chemtool or something like that might dissolve the clog. I really don't want to take the carb apart at all. It could turn into a huge disaster for me.
 
Joined
Jun 24, 2013
Messages
55
Location
Clark, Colorado
When you changed the fuel pump did you change the filter? I second you’ve shaken up junk and sent it moving along the fuel lines.
Change out the filter but as you do blow air down the lines before the filter back to the tank just to air on the side of caution. I used a 60cc syringe to do mine.

Also you can do an okie rebuild to the carb to help suck debrie out although your saying your sight window is correct. But basically w/ the top of the air cleaner off, have a square of cardboard w/ a hole in the middle for the bolt (or take the bolt out), have the truck running not on choke, pull the throttle linkage up to 2k ish as you bring the cardboard down and suffocate the air horn on the carb till it stalls out. Try that a handful of times. It’s a cheapy way to clean out crud before a cloud billowing seafoam to the carb. You can also pull the air horn off and take out the two long jets (as well as the main jets) and careful feed thin wire inside and spray out w/ carb cleaner.
That sounds like something I'll try. Cardboard suffocation to clear the crap out. It makes sense for sure. But I'm also gonna get some SeaFoam or Chemtool and probably a can of spray too. And yeah, I did change the fuel filter, right on the side of the road while I was waiting for the tow truck. Let me ask you this, if the sight window is filled w/ gas, does that mean the carb is getting enough fuel, at least at idling speeds? I ask because the glass appears to filled with fuel when it's idling. I'll let you know how it goes. Gotta get to the parts store.
 

morganism

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Jan 17, 2009
Messages
790
Location
Verde Valley, AZ
 
 
Try the okie trick, then flush the bowl.

Pull the coil wire, isolate it so it wont spark, and get some rags and a bucket. Pump some gas thru the line to the carb, to flush line. EDIT:Look below the sight glass, the two large bolts give access to jets, and drain out float bowl. If you look towards the back of bowl, using a flashlight, not a lighter, you can see the jets lurking like brass eyes back there. Start spraying carb cleaner back there, and work your way around the interior back, trying to blow all the junk out the front bolt hole openings. If you find black rubber chunks, instead of rust flakes, your float is deteriorating.

after you replace fuel line, Do the okie carb trick (ps, you can just use ur palm). Now go pull up on a steep hill, out of the way, where you can back down without causing trouble if it dies, and idle it up high for 10 mins, pulling forward a bit, and letting it roll down, braking hard, and see if it starts dying. If your accel pump diaphram is leaking on carb, order a carb kit. you need to clean it out, and that accel pump fails regularly from ethanol fuel. Buy new fuel filter when in town.

While you have it warmed up, go ahead and check the EGR valve poppet too. Pull the top hose off the egr tophat, put on a longer extension hose, and while idling, suck on it hard for 1 sec or less. Do it 4-5 times in a row. Should almost stall, but listen closely, and you may hear" rocks" tumbling down into your oil pan. That will clean it for another year.

EDIT: My bad, was thinking pull the sight glass, when you should only pull the jet access bolts.
 
Last edited:

NeverGiveUpYota

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You don’t need to pull the glass cover. Don’t even try. Once you remove the screws and the metal oval the glass is by itself and is pressed in with an o-ring under it. The risk of breaking the glass is pretty big. It’s tight as hell. I’ve tried and it’s not as easy as it would appear so I left mine alone.
You can very simply open up the two bolts that are at the base of the bowl. (This is how you can access the two main jets). Fuel will spill out. The main jets are the two small brass plugs seen in my last photo that can be removed w/ a flathead. The holes in them are much larger and a bottle of carb spray w/ the straw attached can get a good stream into them.
The slow jets are accessed once you open the air horn of the carb (the top section). Those are the two you can feed a very thin wire into and make sure they don’t have debrie caught inside.
HTH.

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Last edited:

NeverGiveUpYota

Dare me.
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Messages
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East Hampton, CT
 
There’s no accelerator pump diaphragm. There’s an accelerator pump... and it might be old and worn out. A new one from your dealership is best over an aftermarket one as the material is leather on the oem one and rubber on the aftermarket. Leather is preferred cuz it slides much smoother. It can easily be swapped out w/ carb on the truck.

Acc Plungers.JPG
 
Joined
Jun 24, 2013
Messages
55
Location
Clark, Colorado
Thanks for the detailed instructions. I can't take the carb off, as I'm working outside, and the ground is covered w/ snow. I'm afraid if I get to a point where I've taken too much stuff apart, I might just get screwed, and end up with it not running at all. The glass shows plenty of gas in the bowl, I did get a can of B-12 spray, and blasted short sprays in carb, it didn't make any noticeable difference. It still starts right up and sounds smooth. I'll report on my progress, or lack of.
 
Joined
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Messages
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Most likely it’s getting enough but still might have chunks or debrie in the jets.
I was getting ready to do the cardboard/stall procedure, when my friend showed up and convinced me to drive it at high speed for a few miles. He followed me in his Ford Expedition with a tow strap, just in case.. Got up to about 55mph with no loss of power at all, engine seemed to be getting enough fuel through all the gears, so it seems the SeaFoam and carb spray actually worked. I've never used that stuff before, but, I saw a video on their website that convinced me to give it a try. A friend of mine told me he has used it for years on snowmobiles, and that if the clog is pretty small, it will dissolve it...hmm. If the rig runs well tomorrow on a trip into town(12 mi.) and returns with no issues, I'm calling the case closed for now. Overall, the new fuel pump makes it much faster to start, and it seems to have a little tiny bit more pickup. I think the diaphragm on the old one must have been going out for awhile, but I never noticed until it just quit.
 
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