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Low power at start, fuel filter not full

 
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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Sat Jul 17, 2010 1:12 pm    Post subject: Low power at start, fuel filter not full Reply with quote

I am having issues with my fuel. When I step on the gas at start or low speed the bronco sort of bogs down until the higher rpms are reached.
I replaced the mech fuel pump, thinking this was the case, no such luck. I also replaced the fuel filter.

I notice the fram clear fuel filter is hardly ever full of fuel. Is this a clogged pick up in the tank? Or is it something else entirely.

I recently replaced my carb to a 500 from a 625cfm. I am runing an edelbrock. The engine is built and has hot cams. No idea what was done to the engine. however the po said it cost him something like $11k. I think it has a 302 block and 289 heads??? But not sure.

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Brandon
BFix Locked and Loaded
BFix Locked and Loaded


Joined: 09 Jan 2002
Posts: 2195
Location: USA, Australia, Bahamas, Mexico, New Zealand, & Sandy Oregon

PostPosted: Sat Jul 17, 2010 3:53 pm    Post subject: Reply with quote

Sounds like it could be a timing issue. Try adjusting the vacume advance or see if you are getting any vacume from the carb.
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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Sun Jul 18, 2010 4:39 am    Post subject: Reply with quote

Brandon wrote:
Sounds like it could be a timing issue. Try adjusting the vacume advance or see if you are getting any vacume from the carb.


How do you adjust the vacuum advance? Is this the same as spinning the dizzy? I have been chasing the fuel issue and timing around since I bought the EB a year ago. At times I have full power, and then when all seems like it's adjusted good, it either bogs down or it races.

I don't have a manual, and I can't get one where I live.

Thanks,
Matt

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Stan
BFix Locked and Loaded
BFix Locked and Loaded


Joined: 29 Jun 2004
Posts: 3469
Location: Boring Or

PostPosted: Sun Jul 18, 2010 6:11 am    Post subject: Reply with quote

What carb do you have ?
What distributor?
What gear ratio?
What size tries?
What transmission?
Where is your initial timing set?
Stan

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Brandon
BFix Locked and Loaded
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Joined: 09 Jan 2002
Posts: 2195
Location: USA, Australia, Bahamas, Mexico, New Zealand, & Sandy Oregon

PostPosted: Sun Jul 18, 2010 7:43 am    Post subject: Reply with quote

You are going to need all the details of what you have. Some distributors you can adjust the advance by pulling the hose off and insert a hex wrench. Some you can play with different weight of springs in the distributor. It could be as simple as replacing the hold down nut. Which I had happend to me once, every time I would adjust it, then drive the rig it would be great for a while. Then over time would get worse as it slowly rotated around due to poor holding strength. Then there is also checking to see if you are even plugged into the correct port on the carb. Some ports are constant vacume and some change as the rpms go up. You could also be in the correct port but it isn't creating enough vacume to kick the advance over. Then you have to try adjusting the carb in differnt idling and play with the rotation of the distributor. There is a lot of tinkering needed in some of these motors some times due to the cam. Process of elimination good stuff Cool
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BroncoDave
BFix Locked and Loaded
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Joined: 03 Nov 2002
Posts: 600
Location: Ridgefield, WA

PostPosted: Sun Jul 18, 2010 8:29 am    Post subject: Reply with quote

Don't overlook the simple things like old weak vacuum and pcv hoses.
I once had the hose from the pcv valve to the carburetor that would collapse, or suck closed. This alone had my truck idle and low throttle conditions jumping all over the place, one day idle was great, next day felt like crap. No matter how many times I adjusted the carburetor or timing it would constantly change.
And the fuel filter having air inside is normal on my Bronco.

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regshawn
BFix Locked and Loaded
BFix Locked and Loaded


Joined: 21 Jan 2006
Posts: 869
Location: Portland

PostPosted: Sun Jul 18, 2010 8:35 am    Post subject: Reply with quote

Also if your looking for a little more "Local" help in working on it there are a ton of guys willing an able over on this site. http://northwestclassicbroncos.com
And I had a similar problem with my 72 1/2 ton truck years ago, after checking everything I could I found it to be my vacum hose.

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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Mon Jul 19, 2010 8:01 am    Post subject: Reply with quote

Stan wrote:
What carb do you have ? Edelbrock 1403 500cfm new
What distributor? Mallory uniflight 9000 with matching mallory coil
What gear ratio? Not sure
What size tries? 33"
What transmission? 3 spd auto
Where is your initial timing set? Not sure
Stan


I don't think this is a gearing issue, as when I do get it adjusted correctly, this thing screams and throws huge rooster tails in the sand dunes...However the adjustment is usually short lived. the engine has about 8k on it since rebuild.


Regshaw.. The bronco is in Baja California, Mexico. So NWbronco is out.

i think I may be picking up a 70's EB this week, it is missing the motor. I am going to try and get it for $5000 pesos. or about $420 US. I want it for parts the front is a dana 44. I still have a 30.


Thanks,
matt

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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Mon Jul 19, 2010 8:03 am    Post subject: Reply with quote

BroncoDave wrote:
Don't overlook the simple things like old weak vacuum and pcv hoses.
I once had the hose from the pcv valve to the carburetor that would collapse, or suck closed. This alone had my truck idle and low throttle conditions jumping all over the place, one day idle was great, next day felt like crap. No matter how many times I adjusted the carburetor or timing it would constantly change.
And the fuel filter having air inside is normal on my Bronco.


Thanks..I will check out all the vacuum limes to see if they are bad.

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Stan
BFix Locked and Loaded
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Joined: 29 Jun 2004
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Location: Boring Or

PostPosted: Mon Jul 19, 2010 8:16 am    Post subject: Reply with quote

Don't forget to look at the dizzy hold down bracket. I Also had one that wouldn't stay tight and the timing would change.
Also had a similar issue when I had varying fuel pressure with a bad electric
fuel pump. You could put in a fuel pressure gauge
and check it.
When it quits throwing rooster tails do you have trouble restarting it or does it just run crappy.
It still does this with the carb change ? Do the plugs look fouled when it runs bad?
Stan

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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Mon Jul 19, 2010 12:03 pm    Post subject: Reply with quote

Stan wrote:
Don't forget to look at the dizzy hold down bracket. I Also had one that wouldn't stay tight and the timing would change.
Also had a similar issue when I had varying fuel pressure with a bad electric
fuel pump. You could put in a fuel pressure gauge
and check it.
When it quits throwing rooster tails do you have trouble restarting it or does it just run crappy.
It still does this with the carb change ? Do the plugs look fouled when it runs bad?
Stan


the bronco starts up easily once warm. it takes a while to get it going first. Where should the automatic choke be. lean or rich? I am at sea level and it is currently 93 degrees with 36% humidity. We live on the tropic of cancer.

The bronco has run the same with both carbs. It runs a little better with the 500 than the carter 625.

I just put a new mech fuel pump in thinking this was bad. It is a 5-7psi pump. Is this enough.

Once the secondary's open up I have plenty of power, but it bogs with the primaries. Could I have a clogged metering rod?

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Formerjughead
BFix Locked and Loaded
BFix Locked and Loaded


Joined: 22 Nov 2004
Posts: 2912
Location: Chico California

PostPosted: Mon Jul 19, 2010 4:02 pm    Post subject: Reply with quote

There were three things that I did when mine was doing this:
Replaced all vacuum caps, advanced the timing, adjusted the vacuume on the carb and fiddled with the accelerator pump. Even then it still did it if I got on it too quick from a stop.

Since I installed my kickdown rod it hasn't done it at all.....go figure

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Scodge
BFix Locked and Loaded
BFix Locked and Loaded


Joined: 30 Mar 2005
Posts: 1159
Location: Santa Barbara

PostPosted: Tue Jul 20, 2010 6:08 pm    Post subject: Reply with quote

I assuming you're not running a points distributor, because that would be the problem right there.

Have your tried to adjust the carb for your motor? Here's the manual, you should read it. It will run the engine right out of the box, but not perfectly, especially if you have stuff like a "Hot Cam"
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

Your problem sounds more like timing to me, but the fact that the fuel filter has no gas in it is interesting. Do you have a fuel pressure gauge? You should, because it's impossible to tell if your fuel pump is working properly without it. Just get a little inline gauge and plumb it into your fuel line, and it should read 5-7 psi. Just because you installed a new pump doesn't mean you know you're getting enough fuel pressure. The pump could be bad, improperly installed, or the fuel line could be blocked; or, the eccentric on the cam that drives the pump may be ground down (unlikely).

You should disconnect your vacuum advance. That's always the last thing you connect when tuning your engine timing. Plug all the vacuum ports in the carb and see how she runs. If the problem persists, check the fuel pressure, fuel delivery, and engine timing. You should also read the manual and adjust the carburetor. Route all your plug wires to minimize wire contact and crossing, and away from ground sources to prevent voltage leaks.

Good luck, this stuff can be a cast iron bitch to chase down, but don't replace any more parts until you do some diagnostic work.

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[0===0] '67 ragtop, 5.0 EFI, PS, PDB, D44 front axle, faded blue paint and rusty floorboards.
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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Wed Jul 21, 2010 7:52 am    Post subject: Reply with quote

Thanks Scodge. I will check out everything you mentioned. big thumb up fedup
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Matt
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los cabos bronco
Bfix Carb'd
Bfix Carb'd


Joined: 18 Nov 2009
Posts: 119
Location: Los Cabos, Baja..Seattle, wa

PostPosted: Wed Jul 21, 2010 10:35 am    Post subject: Reply with quote

I found a split in the seal where the vacuum line goes into the brake booster on the line that comes off the back of the carb. The split looks clean and straight, however is it supposed to be there? the brake pedal is squeshee too!! hopefully this crack will fix both issues...yeah that'd be the day big thumb up
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