Cranks, no start, no fuel pressure or pump.

[Big_Joe]

i picked up a 2011 S4 with an apparent seized engine, I removed all the plugs drained the oil and changed, was dirty with carbon but no signs of metallic flakes. charged the battery and tested it, was good and attempted to crank, and sure enough if cranked over like no one's business. then went on to do a compression test, compression was 130ish -150 psi so that checks out. hooked up scan tool had previous code for misfire on cylinder 3, intake manifold runner control stuck closed, and fuel pump module control circuit open. fuel rail pressure is at 13psi.

tested the fuel pump and it runs no problem when supplied 12v ( reading was at 350ish psi after priming with power probe), checked the plug and get no reading. checked the fuse is good, but not getting 12v with ignition on or while cranking. checked all the relays under the cowl, under kick panel ,and in trunk compartment ( I cant find where the fuel pump relay is suppose to be)and they are operating as should and have 0.000 resistance (good). I cant find any wiring diagrams at all for these cars for the fuel system.

Am I missing something?



P.S. I have an idea why the engine appeared to be seized (coolant leak), because even after i got it to crank over many times without a hiccup, as soon after priming the fuel system with the power probe and getting rail pressure it sputtered and locked up again, so i removed a coolant line and pressurized the cooling system with air to evacuate any remaining coolant in the system and attempted to start it and again without an issue it cranks but still no fuel pump or pressure. - I was wrong

SOLVED: It ended up being the fuel pump control module. The reason I believe it to have been locking up was due to the pressure build up in the HPFP (high pressure fuel pump). With the HPFP being run off the cam it would hydrolock the HPFP piston and stop the engine due to the timing chain running the cam. There was no coolant leaks into the engine, the PVC had no coolant leaks and the supercharger held pressure.

[Big_Joe]

Update: so I checked the the wiring and its good, I have power and ground to fuel pump control module, but 0 voltage to fuel pump plug. Figure it's probably the control module. I primed the engine again with my power probes during fired the engine up it ran for about 5 seconds smoothly and then stop, attempted to restart the engine and again it's "seized" I removed the supercharger amd inspected for coolant. I didnt see any signs of coolant the valves were wet tho. The last time this happened I removed coils and plugs and cylinders were empty, but it still wouldn't crank, until I blew out what remaining coolant I thought was left.so removed the thermostat front cover and the water pump and I got about 1-1.5L of coolant out and the last time I got about the same. What else could be stopping the engine from turning over when running. No belts are on either. I'm completely lost on this.

[henri12]

Have you tried pulling the codes?

[S4tinlife]

Update: so I checked the the wiring and its good, I have power and ground to fuel pump control module, but 0 voltage to fuel pump plug. Figure it's probably the control module. I primed the engine again with my power probes during fired the engine up it ran for about 5 seconds smoothly and then stop, attempted to restart the engine and again it's "seized" I removed the supercharger amd inspected for coolant. I didnt see any signs of coolant the valves were wet tho. The last time this happened I removed coils and plugs and cylinders were empty, but it still wouldn't crank, until I blew out what remaining coolant I thought was left.so removed the thermostat front cover and the water pump and I got about 1-1.5L of coolant out and the last time I got about the same. What else could be stopping the engine from turning over when running. No belts are on either. I'm completely lost on this.

Had the same issue not too long ago and it was the module that I had to replace. No issues after that.

[Big_Joe]

Have you tried pulling the codes?

In my original post I noted the codes for misfire cylinder 3, intake manifold runner stuck closed, and fuel pump control module open circuit, I cleared then and nothing was coming back while cranking engine.

[Big_Joe]

Had the same issue not too long ago and it was the module that I had to replace. No issues after that.

Before you replaced your control module it would lock up your engine as well or it just would crank and not fire!

[S4tinlife]

Before you replaced your control module it would lock up your engine as well or it just would crank and not fire!

It'd lock up after several tries.

[Big_Joe]

It'd lock up after several tries.

thats so strange. because i could crank mine all day long and it would crank but as soon as i applied 12v to the fuel pump and pressed start it ran and then would stop and then lock up, but the first time i blew shop air through the cooling system and removed about 1L of coolant and it would crank over no issue and then again the second time it happened i remove the water pump return outlet and the water pump blew out another 1L of coolant it would crank over, but there was never anything in the cylinders. Im baffled

ive removed the supercharger pressure tested it, didnt notice any signs of a leak. removed the PCV under the super charger and there is not coolant under there either, drained the oil and there was no coolant in the oil, but it seemed like there was a mixture of something in the oil because there was dark black oil and then what appeared to be the fresh oil (yellowish), it was kind of separating like water and oil. i mixed it up and poured it into a jar to see if it would separate, but it kind of appears to have just mixed together.

ill try reassembling and try and new fuel pump control module.

[Big_Joe]

Update. I installed a new fuel pump module and it runs without locking up. I edited my original post to save scrolling

[a4lownslow]

Update. I installed a new fuel pump module and it runs without locking up. I edited my original post to save scrolling

What’s the mileage and what’d you pay with a supposed “seized” engine?

I just bought a 2010 S4 6 speed sight unseen through Manheim. I feel like I paid a good price assuming worst case scenario. 147k. I’ll know what I have in a couple weeks once it’s delivered.


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[Loe]

fuel pump control module, is this the controller box in the trunk or the G410 sensor at the HPFP?

[Big_Joe]

What’s the mileage and what’d you pay with a supposed “seized” engine?

I just bought a 2010 S4 6 speed sight unseen through Manheim. I feel like I paid a good price assuming worst case scenario. 147k. I’ll know what I have in a couple weeks once it’s delivered.


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i traded a 335xi i picked up for $4000CDN spent around $2000 to fix, taxes, powder coat winter rims and one new Xice tire. so about $6000. the S4 has 137,000km/85127 miles. came with original rims and a set of brand new rotaform rims with pilot super sport tires. stage 2 unitronic tune with pulley upgrade.

[Big_Joe]

fuel pump control module, is this the controller box in the trunk or the G410 sensor at the HPFP?

the fuel pump control module is under the rear seat on the passenger side. i believe its referred to as the (J538) was $175 CDN/$117USD shipped to Ontario, Canada from Europaparts.com ordered on friday suppose to arrive tomorrow.

[a4lownslow]

i traded a 335xi i picked up for $4000CDN spent around $2000 to fix, taxes, powder coat winter rims and one new Xice tire. so about $6000. the S4 has 137,000km/85127 miles. came with original rims and a set of brand new rotaform rims with pilot super sport tires. stage 2 unitronic tune with pulley upgrade.

Nice that’s a steal.. with that mileage that’s ~ $15000 car USD.

I paid $5500 for mine plus $1000 shipping. I buy and sell these cars (first b8 s4 here), and bought this one as a personal project to enjoy for a few months. I’d value it around $11,000 retail.


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[a4lownslow]

the fuel pump control module is under the rear seat on the passenger side. i believe its referred to as the (J538) was $175 CDN/$117USD shipped to Ontario, Canada from Europaparts.com ordered on friday suppose to arrive tomorrow.

How do you know there are no others internal issues if you don’t have the part yet? Your updat in original post made it seem as though you already replaced the part. Considering the value of that car and what you paid you’d think previous owner would have had a proper diagnosis (by Audi maybe? Lol) to differentiate between “seized” engine and no fuel pressure.


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[Big_Joe]

How do you know there are no others internal issues if you don’t have the part yet? Your updat in original post made it seem as though you already replaced the part. Considering the value of that car and what you paid you’d think previous owner would have had a proper diagnosis (by Audi maybe? Lol) to differentiate between “seized” engine and no fuel pressure.


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My brother has an a4 so I took the module from his and tried it and it fired up and ran, no issue. I ran it for about 30 -45 second as it was about 2L low on oil (drained some to check for coolant) I had oil oil pan off and there was no signs of damage (metallic flakes/chunks) compression was good, removed valve cover and inspected valves, scoped cylinders, removed and pressure tested super charger, removed and inspected pcv for coolant. There was a code for an open circuit in the fpcm why they didn't, look at that is beyond me. It was the first thing I checked, but didn't expect it to hydrolock the HPFP and make it lock up. Because it was cranking after I charged the battery but after I ran the LPFP it would run for 5-8 seconds and lock up and the starter couldn't turn the engine over and an engine can't unsieze its self, Still need to pressure test the cooling system but doubt there is any issues as it would most likely show up else where. (SC,PCV,OIL)

[miztahsparklez]

I wonder if this is my issue. Dealer says engine is seized... However, it just died on me while I was driving and everything else is looking to be fine.

Did e85 kill my 2012 pump? I have no codes... No signs of anything. Is this module just under the seat cover? My car doesn't crank either.

How did you release the fuel pressure at the hpfp?

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[Big_Joe]

if you brought it to the dealer good chance it is seized, I cracked the high pressure fuel line fitting at the HPFP and wrapped a rag around the fitting while turning it off to relieve the pressure. once the pressure was gone it would crank over, it was being hydrolocked by me priming the low pressure fuel pump. But I recently pulled the engine to fix a timing chain rattle (failed tensioner) and I decided to inspect the bottom ends, glad that i did. because it spun all the rod bearings, so now I am disassembling and measuring everything to see whats good and what needs to be replaced.

[miztahsparklez]

if you brought it to the dealer good chance it is seized, I cracked the high pressure fuel line fitting at the HPFP and wrapped a rag around the fitting while turning it off to relieve the pressure. once the pressure was gone it would crank over, it was being hydrolocked by me priming the low pressure fuel pump. But I recently pulled the engine to fix a timing chain rattle (failed tensioner) and I decided to inspect the bottom ends, glad that i did. because it spun all the rod bearings, so now I am disassembling and measuring everything to see whats good and what needs to be replaced.

Unfortunately mine still didn't crank even with the hose pinched off and pressure removed. I couldn't even turn by hand, so mine was really seized. Oh well. It was a nice wish...

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