Fuel Accumulator Part numbers

[sgjii]

For my 80 Scirocco restoration I was going to go all new in the fuel delivery system, from tank to pump to accumulator. AutohausAZ seems to have the best prices on the accumulators but there is a VIN split showing two different part numbers. I happen to have the early part number 0438170019 ($155), I removed it to verify the number. I also have a 1980 Audi 4000 5cyl and I am questioning the accumulator based on a slow to start situation and in light of troubleshooting and other replacements in the fuel system. The Audi is in the same boat with a VIN split and lists the same two part numbers. I removed the accumulator from the Audi and it is the later part# 0438170027 ($135). Upon physical inspection and measurements of the housing, they are the same unit externally with the same dimensions and same sized and located fuel ports.

My quandary is related to the difference between the two units beyond the price differential. Early and late production MK1 & MKII Scirocco fuel injected cars have the same part numbers for fuel pumps and check valves. To even further muddy the waters, the later production MKII Scirocco had yet a third part# 0438170040 appear in 1984, this being the cheapest at only $89. From 84-87 the listing shows both the 0438170027 & 0438170040 units with a caveat of check your existing number.

My 1981 Scirocco is running a 0438170027 accumulator, unknown pump and has CIS-E and a 2.0L 16V.

My theory thus far is this: The fuel pumps changed and improved over time and all end up superseding to the latest pump revision, even up through 16V Scirocco cars. The CIS injection system improved and changed over time as well. I think the reason for the different accumulators is that older pumps need the accumulator they would have had at production and that a newer series accumulator on an older pump might be the catch and I would further assume newer series pumps can use the newer or older accumulators. The only thing I think the difference can be is about fuel pressures and/or delivery rates of the pumps. Even the newer 84up per-pump in the tank systems specify the same main pump number as the older cars and has the same caveat of two different accumulators and "check your existing part#".

Based on this concept and that two of my cars have new/latest part# pumps, I think I can upgrade to the newest and cheapest 0438170040 Accumulator at only $89 from AutohausAZ. I am also questioning how much a difference any of this makes since I have a way newer engine with older and some unknown part versions.

If you have some additional info, knowledge or insight, I would welcome some ideas and input before I place an order.

Stephen

[Chris16vRocco]

I think that as long as the lines connect properly, any of them should work. I put the accumulator from my 88 16v on my 80 and it works fine. It was a different size, so I had to mix/match mounting brackets.

[sgjii]

I haven't had one of the 0438170040 units in my hand for comparison of dimensions but the 0438170019/040 units are the same external dimensions.

The brackets between the Scirocco and Audi 4000 were different but the accumulator would fit either bracket.

Your 16V unit, was it a different physical dimension versus your 1980 or was it a fuel line connection difference?

[Chris16vRocco]

The connections for the lines were the same, but the physical size of the 88s was much smaller.

[sgjii]

I didn't find a part number reference for an 88 Scirocco. Do you know the part number of the smaller unit you have/had?

[sgjii]

I dug out my old "Parts Place for VW" catalog and was reading in the fuel delivery section. That publication indicated that the accumulators were interchangeable, even the small diameter units with older larger diameter units. In fact they sell a new, smaller diameter canister with a rubber sleeve/spacer so it will fit the older bracket for $129. My copy of the catalog is dated spring/summer 2011.

I ordered the $89 new Bosch unit from AutohausAZ part#0438170040. I plan to first install it in my 1980 Audi 4000 5cyl, replacing an original 0438170027 unit. If all goes well then I will use the same unit when I put together my 1980 Scirocco and replace the original 0438170019 unit.

Honestly, I am not sure either unit is bad as they both look decent on the outside. The Scirocco unit only has 55k miles on it and the Audi unit only has 12k miles on it but both are original equipment with the cars from 32 years ago. The Audi I am chasing a delayed starting issue and the Scirocco is going to have a completely new fuel system so I am going to replace the accumulator just because. I am going to test the Scirocco unit in the Audi and see what results I get...

I will post updated results and possibly even 2 used accumulators for sale depending on the outcome

Stephen

[crsmp5]

the differance in the numbers is from a differance in pressures each has... the injectors pressure is also different and should be matched to the split..

the issue is a hot start issue when mismatched going one way vs the other... aka one makes enugh pressure to open up the lower pressure injectors on a hot summer day.. just cannot rember which was higher/lower pressure..

as for the cis-e later style.. all cis-e is smaller and causes hot start issues on hot summer days when put on a cis system.. so doimng that is not a great idea... you can use cis one on a cis-e car.. but not vice versa..

[mr.brown]

the differance in the numbers is from a differance in pressures each has...

What he said. Although specifically in the residual or rest pressure.

According to the Bosch e-catalog the part numbers are:

0438 170 019 mk1 up to 1/80
0438 170 027 mk1 after 1/80
0438 170 040 mk2 8v (and possibly 16v to 6/87)
0438 170 042 mk2 16v 7/87 on

The book "How To Tune and Modify Bosch Fuel Injection" has a table of rest pressures for various cars, notably

Jetta/Rabbit/Scirocco to 1979 - 23 psi

Jetta/Rabbit/Scirocco 1980 and later - 35 psi

Those figures were from the edition revised in 1992 and there are no separate figures I can see for the mk2 - 8v or 16v.

[sgjii]

I think I may have learned something the hard way about specific part numbers...

I purchased the $89 0438170040 and installed it on the Audi 4000 when I took it out of hibernation this weekend. The car does not start for crap now, hot or cold. Runs great but lots of cranking to get it to start.

I just ordered the specified part number 0438170027, which also matches the old unit, for $143.38 (local since it was out of stock at Autohaus AZ for $125). Hopefully install of the designated part number will return the car to starting well most of the time if not solve my original occasional hard starting issue.

Since the fuel pump is brand new, original Bosch, ordered from the correct part number and has a new check valve with it; when I couple that with the correct accumulator I hope to be happy again.

If I continue to have hard start issues, any suggestions on where to go next? Perhaps another check valve in the system?

[Legoguy]

I think I may have learned something the hard way about specific part numbers...

I purchased the $89 0438170040 and installed it on the Audi 4000 when I took it out of hibernation this weekend. The car does not start for crap now, hot or cold. Runs great but lots of cranking to get it to start.

I just ordered the specified part number 0438170027, which also matches the old unit, for $143.38 (local since it was out of stock at Autohaus AZ for $125). Hopefully install of the designated part number will return the car to starting well most of the time if not solve my original occasional hard starting issue.

Since the fuel pump is brand new, original Bosch, ordered from the correct part number and has a new check valve with it; when I couple that with the correct accumulator I hope to be happy again.

If I continue to have hard start issues, any suggestions on where to go next? Perhaps another check valve in the system?

Any update on this? I'm trying to figure out which part that my '88 Cabriolet with a 16V PL swap would need. It has the original CIS-Lambda expansion tank, accumulator, in-tank pump and a replacement "universal" Bosch main pump; then goes CIS-Motronic from the fuel filter forward. I'm thinking it would probably work with all available accumulators due to the CIS-Motronic being a later system.

[Chris16vRocco]

The VW part number for a JH 8v Mk2 is 431-133-441-C, whereas the number for a 16v PL engine is 853-133-441. The 78 and earlier models used part number 431-133-441-B. The B suffix does not supercede to the C according to VW, so I'm not sure what the differences are, if any.

The 8v one fits 79 and later 8v A1s, and some A2s and Foxes as well. The 16v one is listed for A2s primarily. I suspect that the difference is a CIS/CIS-E thing. The accumulator for CIS-Motronic cars (with the 2.0 9A 16v) is a 447-133-441. So I'd say that the accumulator should ideally match the fuel system you're using. A car with CIS-Motronic should use the one from a 90-92 Mk2 16v (9A 2.0) or B3 Passat 2.0 16v (9A).

[sgjii]

I have done nothing else to the fuel system since I took the 4000 out of hibernation. Now that I have put a trip to the Carlisle, PA Import show and about 1000miles more on the car, it is starting and running as well as it did before the accumulator change so I am not as condemning of the newer part number accumulator as I was.

I think my problem is elsewhere in the CIS. I had received advice to replace the check valve, plunger and seals by means of the fuel distributor rebuild kit offered by MK1 Autohaus for around $59. I was told the O-rings get funky on the plunger associated with the check valve and operate poorly. This item is directly related fuel pressures so it makes sens as a point of interest.

My next step I plan to pursue is to put a fuel pressure gauge set on and see what the pressure is in various states of hot, cold, resting, running and check for pressure bleed off. I think this is a better approach than throwing more parts at it yet. I can also do comparative pressure readings between old and new accumulator.

Stephen