| Author |
Message |
Mely
Samba Member
Joined: October 04, 2024
Posts: 29
Location: Worcester, MA
|
 Posted: Sat Jul 19, 2025 11:48 am Post subject: Re: Official Fuel injection questions thread |
 |
|
Sorry, but I'd love to be directed to a test for fuel injector leaks.
I'm really having trouble searching this sticky.
And since I'm here, from my understanding, a leaky fuel injector can be fixed by cleaning (sending out for service). Only reason to replace an injector is because it's cracked, right? Then I'm required to replace all four, not just the one, or more, that are unserviceable?
Thanks in advance.
Edit:
I have the coil disconnected, and each side injector in their own baggie, cranked 5 seconds.
Is it correct that more than 2 drips in a minute is not ok?
Or should there be no dripping in this situation? |
|
| Back to top |
|
 |
busdaddy
Samba Member
Joined: February 12, 2004
Posts: 52767
Location: Surrey B.C. Canada, but thinking of Ukraine
|
| Posted: Sat Jul 19, 2025 12:56 pm Post subject: Re: Official Fuel injection questions thread |
|
|
You are almost there, aside from the cranking... unless the wire you disconnected from the coil was the single white trigger wire.
Injectors in bags, key on, depress flap in AFM with a chopstick or screwdriver to run fuel pump momentarily. No drips are acceptable. Even better with a fuel pressure gauge attached then you know if the system is holding pressure.
They sometimes respond to cleaning, but not usually when leaking, if you have a few used spares you could try and sub one in for the dribbler, but it's better if you can have it cleaned first so you know the flow rate. NAPA has new injectors, I don't know the part number off the top of my head, but it's mentioned in this thread multiple times.
There could be a detailed test on Ratwell.com, I can't remember, although it looks like a bus website all the FI jobs also apply to Beetle, same system.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
|
| Back to top |
|
|
Mely
Samba Member
Joined: October 04, 2024
Posts: 29
Location: Worcester, MA
|
| Posted: Sat Jul 19, 2025 1:19 pm Post subject: Re: Official Fuel injection questions thread |
|
|
| busdaddy wrote: |
You are almost there, aside from the cranking... unless the wire you disconnected from the coil was the single white trigger wire.
Injectors in bags, key on, depress flap in AFM with a chopstick or screwdriver to run fuel pump momentarily. No drips are acceptable. Even better with a fuel pressure gauge attached then you know if the system is holding pressure.
They sometimes respond to cleaning, but not usually when leaking, if you have a few used spares you could try and sub one in for the dribbler, but it's better if you can have it cleaned first so you know the flow rate. NAPA has new injectors, I don't know the part number off the top of my head, but it's mentioned in this thread multiple times.
There could be a detailed test on Ratwell.com, I can't remember, although it looks like a bus website all the FI jobs also apply to Beetle, same system. |
The wire that goes from coil to distributor was the one that was disconnected. The pump ran without pushing in the AFM flap, which I hadn't even thought of.
First the injectors were aimed into a water bottle to check for spray pattern. You could see it was spraying, but not the pattern so well at such an awkward angle and through the bottle. Giving up on that test, then injectors were put into bags. I assumed they would continue to leak if there was an issue. After a half hour the left 2 had very little gas in it, the right 2 had zero. Honestly it might have just been residual drips from being bagged quicker than the right side after the failed spray pattern test.
I do feel inexperience is playing a role here.
Can one new injector be purchased, or must all 4 be replaced together, if there was an issue?
Thanks for all your patience, and knowledge. |
|
| Back to top |
|
|
busdaddy
Samba Member
Joined: February 12, 2004
Posts: 52767
Location: Surrey B.C. Canada, but thinking of Ukraine
|
| Posted: Sat Jul 19, 2025 3:07 pm Post subject: Re: Official Fuel injection questions thread |
|
|
If the wire from the distributor was disconnected the injectors shouldn't have done anything, if you got fuel you got problems.
Can you swap in a single used injector from the classifieds?, sure, but keep an eye on the spark plugs in case it's making that cylinder run extra lean. Sometimes saving a couple bucks costs you more in the long run.
The NAPA part number for new ones is 218515, cry once as they say. Avoid the cheap Ebay and Amazon new units, not many actually meet the flow requirements.
The fuel pump should only run when the starter is cranking, or when the AFM flap is off it's stop, if it's running whenever the key is on there's some PO's wiring shenanigans to investigate and correct.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
|
| Back to top |
|
|
Mely
Samba Member
Joined: October 04, 2024
Posts: 29
Location: Worcester, MA
|
| Posted: Sun Jul 20, 2025 10:53 am Post subject: Re: Official Fuel injection questions thread |
|
|
| busdaddy wrote: |
If the wire from the distributor was disconnected the injectors shouldn't have done anything, if you got fuel you got problems.
Can you swap in a single used injector from the classifieds?, sure, but keep an eye on the spark plugs in case it's making that cylinder run extra lean. Sometimes saving a couple bucks costs you more in the long run.
The NAPA part number for new ones is 218515, cry once as they say. Avoid the cheap Ebay and Amazon new units, not many actually meet the flow requirements.
The fuel pump should only run when the starter is cranking, or when the AFM flap is off it's stop, if it's running whenever the key is on there's some PO's wiring shenanigans to investigate and correct. |
Disconnecting the wire going from coil to distributor means the fuel injectors won't spray? Strange that they did then.
BTW the fuel pump was spraying only when cranking not when key was in on position.
What do you mean when you say the AFM flap is off it's stop? Do you mean flap open?
Thanks for tips on new injector sourcing. |
|
| Back to top |
|
|
busdaddy
Samba Member
Joined: February 12, 2004
Posts: 52767
Location: Surrey B.C. Canada, but thinking of Ukraine
|
| Posted: Sun Jul 20, 2025 12:47 pm Post subject: Re: Official Fuel injection questions thread |
|
|
Strange indeed, without the signal from the points no injection happens.
The flap in the AFM not only measures how much air is enetering the engine, it's also a fuel pump switch, anytime it's away from the fully closed position the fuel pump gets power.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
|
| Back to top |
|
|
Mely
Samba Member
Joined: October 04, 2024
Posts: 29
Location: Worcester, MA
|
| Posted: Sun Jul 20, 2025 1:11 pm Post subject: Re: Official Fuel injection questions thread |
|
|
| busdaddy wrote: |
Strange indeed, without the signal from the points no injection happens.
The flap in the AFM not only measures how much air is enetering the engine, it's also a fuel pump switch, anytime it's away from the fully closed position the fuel pump gets power. |
Ok, good to know AFM flap is also a fuel pump switch.
Do you think my injector leak test was user error? Or they actually are leaking?
And yes, you mentioned earlier that I should pressure test, I agree. |
|
| Back to top |
|
|
busdaddy
Samba Member
Joined: February 12, 2004
Posts: 52767
Location: Surrey B.C. Canada, but thinking of Ukraine
|
| Posted: Sun Jul 20, 2025 2:32 pm Post subject: Re: Official Fuel injection questions thread |
|
|
| Mely wrote: |
| busdaddy wrote: |
Strange indeed, without the signal from the points no injection happens.
The flap in the AFM not only measures how much air is enetering the engine, it's also a fuel pump switch, anytime it's away from the fully closed position the fuel pump gets power. |
Ok, good to know AFM flap is also a fuel pump switch.
Do you think my injector leak test was user error? Or they actually are leaking?
And yes, you mentioned earlier that I should pressure test, I agree. |
It sounds like you did it right, but the result says differently since the injector failure acts just like a missed or wrong wire.
To guarantee the findings do it again, I'd suggest unplugging the electrical connections on each injector but that risks needless vintage wiring damage, confirm the single green wire from the distributor points is really the one you are disconnecting and make sure no other wires are stuck to it when it comes off the coil terminal. And use a pressure gauge too if possible, it can tell us lots of things.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
|
| Back to top |
|
|
|
