my 429 is making a sound

[1971ford]

Aside from the nice VROOM VROOM sound it likes to make,
I have recently noticed a thumpidy thump.
It's like "thump thump thump thump". I know, that narrows it down alot
The thump's are maybe 1/2-3/4's a second apart.
I'm not sure when it started but i noticed it today when i was under the hood with it running. It sounds like it is coming from the front of the engine, like the water pump. I thought "exhuast leak" but it seams to come from the front of the engine.
What noise does a water pump make when it is going out? a thumpity thump?

Tomorrow i will stick my stethoscope on it to see where it is coming from exactly and i'll see if i can get video/sound.


It instantly remind me of Robroy's thumpidy thump, but his is louder and more high pitched.

[BobbyFord]

Check fuel pump. There's a little spring inside between the top of the actuating arm and the housing, sometimes the spring breaks and the pump make a little knocking noise.

[1971ford]

Check fuel pump. There's a little spring inside between the top of the actuating arm and the housing, sometimes the spring breaks and the pump make a little knocking noise.

hmmm..
Well i don't use that fuel pump, i have a fuel cell out back with a Holley pump so im not using the stock fuel pump at all. But it's still there... Which reminds me i was supposed to cap it off... i should do that!
So i guess it could be the fuel pump even though i don't use it, ill check!

[FORDification]

Maybe check out your belts and pulleys? Make sure the belts aren't coming apart and that the pulleys aren't bent and allow the belts to run straight.

[1971ford]

That is something i need to check as well, good idea.
One of the few things i did look at was if the pulleys looked straight and they did not seem to wobble or anything but i haven't checked belts.

[fordman]

its probably a rabbit you ran over.

[1971ford]

its probably a rabbit you ran over.

Funny because i'm sure i've ran over tons, so maybe you're right . I was driving behind my dad on a trail in the middle of the nevada desert and watched rabbits literally spit out from under his tires at me.

[george worley]

It might be a PITA to do depending on how many belts are on your engine, but I have removed them to check for water pump,alt., power steering noises. If the noise go away you have found the problem.

[fastEdsel]

If you are using an alternate fuel supply source but your fuel pump is still on the engine I am assuming the pump arm is still on the fuel pump and pumping nothing. I found a "thump, thump" on one of my 390's and it was coming from the pump. You can either take the pump off and put a plate over the hole or just remove the pump, cut the pump arm off and re-install the casing to make it "look" like a pump is there. I found the thump by using an engine stethoscpoe and can be easily done but removing the fan belts is a good idea and can take away other noises that can interfere with checking engine noises with a stethoscope. In fact I wouldn't check another front side of a running engine with the belts on using a stethoscope because when the probe just accidently touches the rotating fan, the resulting blast through the ear pieces will send you scrambling for cover. You can pick out run out alternator or water pump bearings with all the belts on but just be very careful.

[1971ford]

I think you guys are right. i went and checked with the stethoscope and it sounds like it is the mechanical fuel pump. I'll pull it out and make a block off plate.

[Chaseman]

Sorry to resurrect a thread but I'm curious if the fuel pump was the source of noise? Cause I have a very similar sound (thump thump thump thump) and I isolated it to the fuel pump.

[BobbyFord]

Sorry to resurrect a thread but I'm curious if the fuel pump was the source of noise? Cause I have a very similar sound (thump thump thump thump) and I isolated it to the fuel pump.

It's very common for the fuel pump to make noise when the little spring breaks.

[1971ford]

I have yet to remove the fuel pump and block it off to see if that is the true reason for the thumpidy thump (will be a job for next week off of school).I will let you know when i find out.

[Chaseman]

Okay , thanks 1971Ford
Also for the record..
I've already replaced the pump , unplugged the plug wires looking for wrist pin , fairly certain it's not a rod knock (it's been around for years) , it comes and goes throughout the rpm range. I still hear it in the front bottom driver engine of the engine at the fuel pump. I need to run it with out the pump through gravity or something and see if that stops the noise. Soon as our hiatus ends in Mechanics class.